January, 1931 EDDIE HARRIS ; Asks — ; "Are YOU Interested In A WELDED Film Splice — or — Does JUST A PATCH Satisfy You?” ; Our Slogan: "The Splice is Stronger Than the Film Itself,” is not merely a "catch-word” — It means that the break in the film is ACTUALLY welded as steel is welded — FOR PERMANENCY! We feel, at this time, that an analysis of the working of ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT and the i ordinary QUICK DRV INC cements on the market, will clear up i a mis-understanding as to the value of a quick drying cement and ' one of less volatility. [ To WELD a break you must FUSE and MELT the broken pieces into each other to become ONE. To PATCH a break you just use an adhesive to make TW O SURFACES stick to each other k FOR THE TIME BEINO — They will come apart — in the case of film, ether will do that. l Ether being highly volatile, dries quick, hence can only get a surface grip on the film and soon opens! i ODpRLESS- FLAMEPROOF — 2 in 1 FILM CEMENT having low volatility evaporates slower BUT melts and fuses the broken film into a WHOLE. A Film Splice made with 2 in 1 will STICK IMMEDIATELY but WILL NOT stand an immediate PULLING TEST. MAKE YOUR SPLICE— REEL YOUR FILM IN CONFIDENCE— AND FORGET IT! It’s $1.25 a Pint Parcel Post > Also Makers of Truevision Parts, Fire X Liquid, Lens Paste, Rust Remover, Gum Remover, Perfumes, Etc. j 2 CEMENTS INCORPORATED INTO 1 FOR USE ON SAFETY AND ! REGULAR FILMS Hewes-Gotham Co. 520 W. 47th St. New York i One Reason’s Greetings from LOCAL 150, I. A.T.S. E. Officials TED ECKERSON MORT SANDS T( )MMY A R ME NTROUT Los Angeles, 1931 r-vo to all A. P.S. members and their families fr rotn THE MEMBERS OF SAN FRANCISCO CHAPTER No. is i ■«* Three ROLL CALL American Projection Society, Chapter No. 7 V ALFORD. HAROLD E. FOWLER. C. M. ALLEN. CHESTER B. FOY, JOSEPH E. ANDERSON. EARL WING FREYMAN, HANS ANGEL. PERCY GEARY. ERNEST M. ARMENTROUT. THOMAS W. GILLUM. DALE ASHCRAFT, CLARENCE S. GILLUM, JAMES F. BABCOCK. CLYDE A. GRAHAM, JAS. J. BABCOCK. ROLLO D. GRAHAM. KENNETH BACON. RODNEY T. GRAY, STANLEY BANDY, ASA EVERETT GRAYSON, JESSE A. BANTOU. A. F. GREINER, HAROLD LARI BARDEN. E. C. GUMM, LESLIE C. BAUME. FLOYD WM. HASKELL, RAY L. BENNETT, ALONZO S. HAWKER. C. L. BETZ, BYRON H. HAYWOOD, W. GEO. BISHOP, H. C. HELM, J. L. BORCH, FRED L. HEPBURN, W. H. BOTELLO, LOUIS HERMANCE, WM. R. BRERETON, ART HIBBARD. HAROLD G. BRIDGE, WILLARD E. FIIBBERT, FRANK C. BROWN, REX C. HOLBROOK, S. E. BURTON, SIDNEY HOUCK, WM. C. CAGE, HARRY RALPH HUMPHREY. FRED A. CALLAHAN, CLEMENT CHARLES HURTLEY, GREAY CLARK, ROBERT D. JACOBS, EARL CLARK. ROY E. JENKINS. FREDERICK F. CRAIG, J. W. JONES. LAWRENCE J. CROWLEY, W. G. KANE. LE ROY DAUGHERTY, WILLIAM P. KELLER. E. A. DELAY, W. L. KENTON, J. B. EDGAR, HOWARD KNOWLES, GERALD I.. EVANS, GEORGE O. KOSKOFF, D. H. FEINSTEIN, ALBERT LARSON, ROY WALTER FELTS, OTTO LESTER, A. L. FLETCHER. RALPH LEVITT, DAVID B. our ROLL CALL (Continued) I. IX AH AX, JOHX L1XDGARD. HAROLD A. LINDSEY, “JUDGE" M. W. LUCAS, C. M. McBRYDE, FRAXK McC( )X AH E V, ROBERT McCullough, russell li. McGINNIS, JAMES E. MacDONALD, RALPH L. MAHOXEY, PAUL J. MALL LA', ALFRED M. MATTHEWS, LUMAX S. MAXSON, W. J. M EG1XNESS, CLYDE MELLING, RAY MILLER, HAROLD V. MIXNIG, FRAXK R. MOELLE, LOUIS A. MUXRO, K. H. XARATH, ART XEGLEY, E. A. OSBORXE, ROBERT PAGE, GODFREY W. PARIS, PETE PATTQX, W. T. PEXCE, R. D. PERRISEAU, HARRY PETERSOX, LLOYD M. PFAU, JULES R. P1ERSOX, E. R. POIXTXER, D. J. PRESTOX, WALTER PRICE, WALTER J. PULLEX, ALBERT R. PYLES, LEOXARD R. REESE, CHAS. C. RILEY, H. J. ROBB, WILBUR A. ROBBIA'S, ERXEST L. ROB1XSOX, FRED D. ROSS. WILLIAM R. RUDD, DOXALD RUDOLPH, MAX RYDER. CHARLES WILSOX SAILOR, HAROLD M. ST. CLAIR, HAROLD SALYER. CLYDE W. SAWYER. FRANK A. SEARLE, CLARK A. SHROEDER, A. C. SLIPPER, GUY SMITH, ART R. SMITH, HUGH C. SMITH, MARION A. SMITH, RICHARD KENDALL SODERSTROM, ROBERT T. SPANGLER, TED R. STUDLEY, PORTER L. SWANSON, HAROLD G. TARTT, J. J. THOMAS, LA VERX H. TIMMONS, ROBERT D. YEXCILL, CHARLES A. VERNON, ROBERT W. WEAVER, FRED EARL WELLBAUM, JOHX R. WELLS, WILLIAM W. WILLIAMS, DON HARPER WOOD, GLEN M. WOOD, GUY MARTIN WOODARD, W. T. WUTKE, LOUIS M. YOUNG, GEO. H. YOUNG, PURDON C. S? i KrKrtrt* •!•♦!• ♦>♦> ♦>♦> •> v ♦> v v ♦> •> v •> v v ❖ v v v ♦> ♦> v <5* v v v v •> ❖ v »> •> •> »> <> ♦!• •> <• v v •!< v v LOS ANGELES, NINETEEN THIRTY -ONE ®-— Season's Greetings California Theatre Huntington Park, Calif. GEORGE YOUNG FRED BORCH B— S i x NewYear’sGreetings Dawn Post Number 380 AMERICAN LEGION “Your American Legion Post” Officers Commander. P. R. CRAMER First Vice Commander. D. B. Levitt Second Vice Commander B. J. Moody Adjutant Finance Officer F. L. Borch Chaplain . Harry Little Sergeant-at-Arms Jack Staikey Historian . D. J. Pointner Publicity Chas. A. Vencill Legal Chairman Carl A. Kountz Executive Committee E. E. Bennett Lew C. G. Blix Harry G. Henson Membership H. E. Alford Dan. Green Ben Rubein R. D. Babcock Milton Guion Chas. W. Ryder Italo. Benederri Chas. B. Hall Clyde W. Salyer R. J. Benkert W. R. Hermance Art. C. Schroeder F. U. Brown I. B. Keen Jim H. Scott Sidney Burton J. Leigh Kennedy Louis S. Shurtliff Milton Burns Nunxio Loforti Porter L. Studley H. R. Chapman Harley J. Luse Robt. D. Timmins Ed. Dahy Neal Matheson Vince Vingi W. P. Daugherty Frank McBryde Geo. P. Wiggins Edward Dick Henri Monnet Guy M. Woods Dr. D. Dickinson F. A. Porter Harld T. Craig F. A. Draper C. A. Pritchard Geo. Katz Loy B. Evans Chas. C. Reese J. W. Craig Claude Giargiari Herbert Riley M. S. Donnelly James J. Graham Percy A. Rogers Otto Hansen The only Amusement Federation Post in United States , Meets first and third Thursday at midnight at Patriotic Hall. Season’s Greetings United Artists Studio Projection Staff • HILL BRIDGE, Snpt. of Projection GEORGE FREEMAN PERCY BREWER H. C. BISHOP CARL STEMMLER JOSEPH J. (PHOEBE) VARTAN HAROLD SWANSON GLEN ALGER Regards to All from Fox W est (Toast Stud Projection Staff 10s E. L. ROBBINS, Supervisor of Projection C. V. CHURCHILL \\ . F. WEISHEIT KENNETH REED H. K. PORTER AL PULLEN PL C. RODDAN GEORGE HURTLEY E. J. SELVIDGE JOE PIERCE L. J. JONES H. MOHLER Los Angeles, Cali! i 1931 omia A A A A -A. A A A & Nine IN MEMORIAM OUR UNION BROTHER LESTER HESS HAS GONE ON BUT THE MEMORY OF HIS GOOD FELLOWSHIP AND SMILING FACE WILL LINGER IN THE MEMORY OF HIS CO-WORKERS FOREVER A Technical and Educational Publication. Devoted to the Western Projectionist and his Progressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G. CROWLEY H. E. ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE 1264 Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Phone II25W Circulation Volume II. JANUARY, 1931 Number 1 International President Geo. C. Edwards .... 13 In Appreciation 14 President Burton of California Chapter 7 ... 15 President Seavier of Chapter 16 16 Portland Progress By A. E. Jayne 18 Craft Technical Data By A. C. Schroeder .... 19 Retiring Officers 22 Incoming Officers 23 P. A. C. Chief Thad C. Barrows 24 Standard Release Print 25 Nature of Light By Robert D. Clark 26 Nine Months of Progress By J. O. Ellery .... 29 Academy Official, Lester Cowan 32 Generator Tests By R. Van Slyker 40 Chapter Seven Dinner-Dance 41 Co-ordination By P. A. McGuire 42 Things in General By the Editor 48 Pin Spots 49 Chapter Doings 50 Secretary Comments 51 Published Monthly by The California Chapter Number Seven, A. P. S. Distributed Gratis to All Western A. P. S. Members. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Boulevard, Los Angeles, California. Copyright 1930, by Chapter Number Seven, CA. T. 5-. Cos cAngeles, California Eleven S' TOWER THEATRE OWEN F. STOWE i E. W. ANDERSON j CHUCK FOWLER : H. PERRISEAU : j. New Y ear G p e e ling s [ CAMEO THEATRE i ; W. E. PRESTON ; I A. E. BANDY ) i E. R. PIERSON I W. E. DE LAY T -^ce / z' e International President GEORGE C. EDWARDS of American Projection Society Sends Message to Western Projectionists I want at this time to express to the Officers and Members of California Chapter No. 7, A. P. S., my sincere appreciation of the excellent work performed by the Chapter during the year. The Projectionists of the American Motion Picture Theatre had thrust upon them, with inadequate time for preparation, the great responsibility of properly putting over the Motion Picture synchro- nized with sound. Failure on their part meant death to the industry. The outstanding success of the synchronized picture is in no small degree due to the splendid co-operative work of the members of this Chapter. They have spared neither effort or expense in finding remedies for the many imperfections and failures in apparatus and have, through the medium of their excellent little Chapter publica- tion “The Loudspeaker,” distributed much valuable information to the craft. The thoroughly efficient and unselfish work of the Officers calls for the highest commendation and this, in combination with the spirit of real craftsmanship shown by the members, is the greatest asset any organization can possibly desire. The coming years will bring new problems, I feel assured that these will be taken care of by California Chapter with the same energy and spirit they have shown in the past and that the aims and principles of the Society for the advancement of the craft will be upheld to the highest degree. GEORGE C. EDWARDS, International President A. P. S. A. A A A ^ ^ ^ ^ ^ ^-*->*-AAAAAAAAAAAAAAAAA Thirteen In Appreciation ^9 BROTHER SIDNEY BURTON, President of C alifornia C hapter No. 7 A. P. S., whose initiative and perseverance coupled with an unusual amount of execu- tive ability has made the rapid strides of his Chapter possible. Upon his shoulders has rested the Herculean task of guiding the destinies of this organization through the turbulent waters of early existence. PI is course was always a true one, directly toward progress and amicable coordination. H is success has been acclaimed an achieve- ment rarely paralleled and never excelled. We are proud in the knowledge that he will remain at the helm during another year, thus assuring us of another twelve months of progress. And to those other officers who are retiring from office and taking their places among the other members we give our thanks. Theirs is the satisfaction of know- ing a task is well done, their duty performed they are now better fitted to serve as members. We hope that we may some day he fortunate enough to again secure their services as officers. Until then, We Thank You. Co it r t e e n To Officers and Members of Chapter Number Seven A review of the outstanding events and progress of Chapter No. 7 for the year 1930 indicates that as a whole it has been a very successful year. The birth of the ‘A. P. S. Loudspeaker,” the national publicity and recognition we have received, the educational work we have carried on, the increase in membership, the meeting of June during the I. A. Convention, and finally the Second Annual Dinner-Dance and Frolic may well be cited as being milestones in the Chapter’s history for 1930. SIDNEY BURTON President, California Chapter No. 7, A. P. S. It is a sad fact that during the latter part of the year several of our number suffered from the unemployment condition that has prevailed throughout the entire country and these members are no doubt somewhat discouraged. There is, perhaps, no condition so lamentable as the one of a man who possesses ability, industry and ambition who is unable to find adequate vent for these faculties. The majority of our members possess these faculties and it is with great satisfaction that I observe a marked upward trend. It is highly probable that in the near future conditions \ will be so much improved that these unfortunate Brothers will all be lucratively employed. Brothers, at this time it gives me great pleasure to extend my greetings to you. It is my sincere wish that each member of the Society and the organization as a whole shall be blessed with health, happiness and pros- perity throughout the New Year of 1931. Ft f te e n San Francisco Chapter 16 Advancing Rapidly in Educational Work By FRANK L. SEAVIER The next year brings forth many problems along projection lines which have never been taken up by any So- ciety as yet. Our Chapter will en- deavor. during the next year, to solve and explain through professors and engineers, these new problems. So far, our lecture courses, which are held every Tuesday night of each week, are planned over a long period. Many surprises are in store for our members; simplified pictures will be shown for our Society — a television apparatus has been placed at our dis- posal ; amplifier outfits which are of a new type — a new projector which will soon be placed on the market will be shown. Also, we expect to solve, in a clear and concise manner, some of the more intricate screen record- ing amplifying and projection ideas, which 1o some are quite intricate. We aim to have these explained in a sim- ple way, so that they may be under- stood by all of our members. We aiso intend to have a few social eve- nings the next year. During the year 1930, we feel a great good has been done our mem- bers. I wish to take at this time, the opportunity to thank all the officers of San Francisco Chapter No. 16 for the wonderful support they have giv- en me during the year. Also, wish to thank those members who have given their time to make the success of our Chapter which has been made during the last year. Our attendance has been splendid. Along those lines at this time I wish to say . . . Those members from now on who fail to attend the lectures on each Tuesday night are missing the chance to obtain knowledge which they cannot receive S i xte e n FRANK L. SEVIER President San Francisco Chapter 16. from any books which are on the mar- ket now. I want to say that the con- tinued prosperity of San Francisco Chapter No. 16 is placed on the shoul- ders of each and every member. Their interest and their attendance at these lectures are the only way that the So- ciety can succeed. I admonish all members to attend these lectures, as the projectionists now have a great many problems placed on them, which have never been placed upon their shoulders before, and it is due to themselves and the profession as a whole, that they study, attend the lec- tures and carry the thought of the lectures and what they learn in their every day work. Let me here express my own and the Chapter’s deep appreciation of the wonderful lectures and the able man- ner in which they have been delivered before our Society by the Engineers of the E. R. P. I. and R. C. A. Cor- porations, as well as our most genial and learned Professor Reukema, who has given us many hours of his own time to help us solve our problems. I wish to extend to the Loudspeaker and all of the members of Chapter No. 7, my deep appreciation for the many pleasant associations and help which they have given me. PORTLAND PROGRESS By A. E. JAYNE, A. P. S. Although our Chapter, Number 20. is comparatively new, we have accom- plished a great deal in getting a good start for the new year. We have had a number of interest- ing and instructive lectures since our Chapter was formed in March of this year, of whom the following took an active part, in instructing the mem- bers in the study of Projection: Mr. Brisbin, Mr. Knox, Mr. Holcomb and Mr. Omer Wible, who are at this time connected with E. R. P. I. We have recently rented a suite of rooms in the Abbington Building, which we expect to improve and use as a club room for the members as well as for business meetings and lec- tures. We have engaged the services of Mr. Cruze, of the Oregon Institute of Technology, to give our regular lec- tures in the study of electricity. We also have planned to have the new type Simplex and Motiograph mech- anisms, new type lamps and other pieces of apparatus for actual study in the club rooms from time to time. This Chapter is composed of a group of men who are active in the study of this profession and take an active part in all of our meetings. The officers of the Chapter are composed of the following: President, J. T. Moore; Vice Pres- ident, J. C. Porter; Secretary, A. E. Jayne ; Treasurer, W. A. Whitten ; Sergeant-at-arms, J. W. Stuerhoff. The Board of Governors is com- posed of the above named officers, in- cluding L. M. Davis and E. M. Hazel- wood. All of the members enjoy the Loudspeaker very much and find it highly instructive as well as enter- taining. It is a fine medium in keep- E i g h t e e n J. T. Moore, President, Chapter 20, A. P. S. ing all members in touch with the work that is being done by other Chapters. HARRY WENGER PHOTOGRAPHIC STUDIO Extends New Years Greetings to Chapter Seven Eh =iS TRANSFORMERS The Clough System The distortion spoken of last month is not always as bad as it was pictured. Very often this distortion is reduced a great deal in the follow- ing stage. The transformer can be wired in two ways: so that a nega- tive signal on the grid of the first tube produces a negative signal on the grid of the following tube; secondly, so that a negative signal on the grid of the first tube produces a positive signal on the grid of the second tube. When wired in the first manner the positive half wave, which was ampli- fied a very small amount in the first stage, is positive when it reaches the second stage, where it is again am- plified only a small amount, thus be- coming a still smaller percentage of the total signal. If we reverse the primary connections to one of the transformers the positive wave in the first stage becomes negative in the second and so it is amplified normally this time, but the negative part of the signal in the first stage is positive in the second stage, so it is partially suppressed, thus evening up the two sides. This evening up process does not straighten out the distortion caused by amplifying the different portions of the positive wave to a varying de- gree. In Fig. 1 the horizontal line show- ing the strength of the magnetizing force can be considered as milliamps flowing through the primary and through the tube. A represents a current of 1.5 mils; B, 2 mils, and C, 2.5 mils. The letters D. E. and F show the amount of magnetization in the core. The negative half of the signal varies the current from A to B. This causes the magnetization to vary be- tween D and E. The positive wave varies the current the same amount as the negative wave did, .5 mil., but the degree of magnetization only changes from E to F, a value not half as great as from D to E. That is the reason for the distortion. Nineteen Th« total change in the plate cur- rent is 1 mil. If a 1000 cycle tone is impressed on the grid the current variation will be about .1 mil, and it will vary about the verticle line B. When the current is maximum it will be represented by a line slightly to the right of B. 1/80 of an inch to the right of B, if B and C are 1/8 inch apart. When the current is minimum a line the same distance to the left of B will represent the current. No- tice where these two lines would touch the curve, and imagine two lines ex- tending to the right from these two points. They will be slightly above and below the horizontal line E, and nearly equal distances from E. This shows that there will be very little distortion due to saturation of the core. If the 100 cycle tone is reduced so the current variations are the same as for the 1000 cycle tone, in other words, the volume is reduced, then the distortion will be the same as it was for the 1000 cycle tone. Reducing the plate current moves B to the left. If it is moved to a po- sition between A and B the transfor- mer will work with very little distor- tion due to saturation. When no current flows through the windings the troubles due to satura- tion are eliminated. The Clough sys- tem is one way of doing this. Fig. 2 shows how a transformer of this type is wired. There are quite a number of interesting things in connection with this system. i ! 1- - j r -cf ; 0 -* FIG. 2. +c The diagram shows a resistance, a condenser, and the transformer coil, and it appears as though they were three separate devices. Silver Mar- shall puts out a transformer of this type, but the resistance and the con- denser are placed inside the casing that houses the transfo1 mer proper. Externally it looks the same as an or- dinary transformer. There are four terminals which are marked in the regular manner: plate, positive B, grid, and negative C. The resistance performs the same functions as in a resistance coupled amplifier. The main difference be- ing in the value of the resistance, which runs from 20,000 to 50,000 ohms in the Clough type, while that used in a resistance coupled amplifier rarely is less than 100,000 ohms and in modern practice very often goes up to 250,000 ohms, depending on the type of tube preceding the resistance. The low resistance makes possible the use of the same plate voltage used with the ordinary transformer. The condenser not only performs the duties of the ordinary isolating condenser in a resistance coupled am- plifier, but it also becomes a part of a resonant circuit formed by the con- denser and that part of the coil form- ing the primary of the transformer. The primary is the portion of the coil between the tap and the negative C terminal. Neglecting the part of the coil above the tap, we can see that the condenser and the remainder of the coil are in series. The circuit being from the condenser on the tap, down through the lower part of the coil, through the source of C voltage, which is connected to the filament circuit, then from the filament of the preceding tube to the plate and finally to the condenser again. Only that part of the filament circuit is shown that connects positive C to the two filaments. The C voltage may be batteries or the drop across a resist- ance. When a capacity and an inductance are in series the circuit becomes res- onant at some frequency. The fre- quency depends mainly on the values of the capacity and of the inductance. When this circuit becomes resonant it produces a hump on the amplifica- h o o O -o OUT T -tv e n ty tion curve. Not only are the low notes amplified more because there is no DC in the primary, but due to the resonant circuit we can increase them still more, and just where we want to, because we can shift this hump by varying the size of the con- denser. Of course we cannot do so ourself in this particular transform- er, but the manufacturer has taken advantage of this fact and adjusted the various values so that the humn will fall where it will do the most good, somewhere below 100 cycles. This is in the region where the am- plifier becomes less efficient and the loudspeaker response also falls off, so that the rise due to the transformer serves to straighten out the curve of the entire system at the low end. Now that we know how the Clough transformer is built and wired let us see what the action is. DC cannot flow through the transformer be- cause the condenser stops the flow of direct current, and when the tube is operating as it should, there is no current flowing between the grid and filament. Thus there is no DC what- ever in the transformer, so the core does not become saturated. To get the signal into the trans- former a current must be made to flow in the primary, from the tap to the terminal marked minus C in Fig. 2. Since we have eliminated the DC we have only the signal current to contend with, and it is AC. The iso- lating condenser readily passes the AC. If we impress an audio signal across the condenser and the nega- tive C terminal it will be stepped up and transferred to the grid of the following tube. Since the source of C potential is bypassed by a large condenser, connected by the dotted lines from C minus to the filament, we can connect one terminal of the audio input to the filament of the tube instead of C minus. As you will remember the varia- tions of the plate current constitute the signal, and these must be made to vary the charge on the isolating condenser. This is where the coup- ling resistance comes in. The first tube in Fig. 2 draws a plate current of 2.5 mils, which also flows through the coupling resist- ance. Whenever a current flows through a resistance a drop in volt- age takes place. According to Ohm’s law the drop equals the current times the resistance; 2.5 mils (.0025 am- peres) times 20,000 ohms. This gives us 50 volts. The B supply is furnish- ing 90 volts to this circuit, 50 are consumed in the coupling resistance, so there are 40 volts left to supply the plate of the tube. That means a difference of 40 volts exists between the plate and the filament of the tube. One terminal of the isolating con- denser being connected to the plate is also at a potential of 40 volts in respect to the filament. The other side of the condenser is 40 volts neg- ative in respect to the filament. The negative 40 volts is due to the bias put on the grid of the following tube. (40 volts is the proper bias for a ’71 type tube). These two voltages be- ing in series add up, making 80 volts between the two sides of the. con- denser. Since bias voltage in itself does not affect the operation of the transformer we will ignore it, as it will simplify the explanation. So we say there are 40 volts across the con- denser. Let us see just what takes place. When the amplifier is dead, there is FIG. 3 no charge on the condenser. Zero voltage across it. When we light the amplifier a current flows from one (Continued on Page 46) T zv e n ty -one SIDNEY BURTON y*y] KEMT0K • W.&CPOWLCY D.B. LEA.VITT* Sc’»r< 1 he men pictured above have served California Chapter Number Seven well. During the past year they have given unstintingly of their time and energy. Their task is finished. Their remuneration is the gratifica- tion of knowing that their job is well done. During 1930 the activities of our Chapter have expanded immeasurably under their faithful guidance. ( )ur lectures have been of the highest calibre. Our social activities have been heartily enjoyed by the entire mem- bership. By their devotion to the high ideals of our Society they have won the esteem of A. P. S. men all over the country, and particularly they have won the respect and admiration of their brothers of California Chapter Number Seven. Our thanks to them. May all their efforts in their future ventures be crowned with equal success. The men pictured above are the officers selected to guide the destinies of Chapter Number Seven through the next twelve months. By the act of accepting the various offices these men have incurred a serious respon- sibility. Their capability and progressive loyalty in the past has prompted their brothers to select them as their leaders. With only one exception they are new faces. Fresh from the ranks of active members, their ideas will be new, their enthusiasm undaunted by tedious details, and last, but not least, they are each well suited to the positions to which they have been elected. They take office at the first meeting in January. To these men has come a high honor. We con- gratulate them. Under their guidance our Chapter can- not fail to go far and accomplish much during 1931. T xveti ty t h r e e P. A. C. CHIEF SPEAKS ON AIMS By THAD C. BARROWS President Projection Advisory Council It has been gratifying to note the progressiveness of the California Chapter of the American Projection Society and the energetic spirit of its members, which I had an opportunity to get a good “close-up” of during my visit to your city last spring. I have heretofore expressed my ap- preciation of kindness shown me and am glad of this opportunity to more widely approve of your activities. Though not a member of the A. P. S. I am a firm believer in craft and technical societies. I am a member of the Society of Motion Picture En- gineers and the Projection Advisory Council. It was also a real pleasure quite recently to have a chance to closely cooperate with the Technical Bureau of the Academy of Motion Picture Arts and Sciences and their efforts to co-ordinate the technical ac- tivities of this industry. In appoint- ing Harry Rubin chairman, Herbert Griffin and Sidney Burton, members o f the Technical Co - Ordination Committee of the Projection Advis- ory Council, we believe, we have es- tablished an important precedent. It is always wiser to anticipate criticism and by working with the Academy as soon as they start anything which concerns projection, we shall un- doubtedly secure much better results. In my letter endorsing the ‘Stand- ard Release Print,” I said “we believe, from the projectionist’s standpoint that the standard unquestionably rep- resents a step in the right direction.” The Academy undoubtedly has done good work in the “Standard Release Print,” but it can only be successful through the practical co-operation of T iv e nty -f o tir all progressive projectionists. The Projection Advisory Council was compelled to neglect a number of its other activities in order to closely co- operate with the Academy in the work of developing and distributing the “Standard Release Print.” We consider this a highly important task and the Council is always willing to work in the direction which it believes will secure the most satisfactory re- sults. The Projection Advisory Coun- cil has a variety of ideas and plans, most of which have been put into ef- fect to a greater or less degree. The Council will continue to serve in any way which will help raise the stand- ing of projectionists and the stand- ard of projection. We are at any time ready to temporarily abandon our own plans if we can accomplish more by cooperating with other or- ganizations. We have clearly demon- strated that we can secure results which will be of benefit to the pro- jectionists and the entire motion pic- ture industry without coming in con- flict with the work of any other or- ganization. We have had true cooperation from the members of California Chapter, American Projection So- ciety, and Local 150 of the I. A. T. S. E. and M. P. M. O., and they can be assured that the Council will con- tinue to take a deep interest in the advancement of these two organiza- tions. Our activities and interest are international as well as national, but we know of no locality that is more entitled to our hearty support than Los Angeles. With best wishes to all for happi- ness and prosperity in 1931. STANDARD RELEASE PRINT GAINING RECOGNITION AND PRAISE » » » Some time ago the Projection Ad- visory Council decided upon a system of visual changeover cues to be used by all producers. Their recommen- dations have been approved by the Academy of Motion Picture Arts and Sciences and the system adopted. Up to now very few western projection- ists have declared themselves either for or against the system, although the prints so marked have been in use in some localities for several months. The east has been almost unanimous in its approval. Many letters have been received by the New York office of the P. A. C. from eastern projectionists stating their views on the subject. I am printing four average letters which give a fair idea of the general trend of several hundred received and relayed to me. After reading these letters every western projectionist should sit down immediately and write in his opinion and suggestions about the system. Point out the faults as you see them and give praise if you think it is due. Remembering, of course, that the sys- tem was intended to aid the projec- tionist without mercenary intentions and that your criticism should be con- structive and not vindictive out of consideration for the originator’s good intentions. The letters of comment that follow show that the writers have given con- siderable thought to the subject and thereby qualified themselves to dis- cuss the subject. I. A. T. S. E. & M. P. M. O. Local 595 Postoffice Box 187, Carthage, Mo. Nov. 21, 1930. Projection Advisory Council, New York, N. Y. Dear Sirs: In answer to your request that we acknowl- edge receipt of your letter of October 31st, ex- plaining the "Standard Release Print Makeup and Practice,” we wish to say we were very glad to receive both, and having looked through the magazine can say that we feel it will be a great help to every projectionist. We feel that this link between the Council and projectionists will be a great help at solving his problems. Wish to say that the projectionists of this Eocal will be glad to co-operate with you. Yours truly. (Signed I JOHN COMIR, Secretary, Local 595. INTERNATIONAL ALLIANCE OF THEATRI- CAL STAGE EMPLOYEES AND MOVING PICTURE MACHINE OPERATORS OF THE UNITED STATES AND CANADA Local 365, P. O. Box 119, Crawford svi lie. Indiana. November 18, 1930. Mr. Laurence Jones, P. O. Box 98, New York City. Dear Sir and Brother: Received your letter of October 31st, enclosed with "Standard Release Print Makeup and Prac- tice.” Wishing to portray, that since heretofore there has been no consideration afforded the projectionists, we are indeed honored. Realizing the haphazard method of marking film for change-overs, in the past, we feel that since striving to obtain a better reception al- ways, this new system will be a success and can assure you that we will co-operate in accord- ance. However, on account of the very heavy bills, shown here and elsewhere, the problem arises on doubling reels, to counteract the shorts on threading up. We suggest that the doubling of all feature pictures will better the trade as a whole. Wishing your enterprise a hearty success, and affording you our co-operation, we remain, Fraternally yours, LOCAL UNION NO. 365. (Signed) H. HAROLD BELL, Corresponding Secretary. 119 Wynsum Avenue, Merrick, N. Y. November 12, 1930. Mr. P. A. McGuire, 90 Gold Street, New York City. Dear Friend Me.: 1 have your letter of November 5tli, 1930, and the booklet of October 31, 1930, before me. I think the booklet is a very fine piece of work. This booklet, "Standard Release Print Makeup and Practice,” is well written and describes very well the work that has been done by this committee. So many producers have gone to the trouble of printing a fine leader and made the number of the reel so small that it can hardly be seen. It must have taken some time and trouble to get all these producers to agree on a standard. All of them were so very far away from anything that looked like a stand- ard. This will be a great help to every pro- jectionist and it will also be a great joy to the audience. The click system now in use is a great failure. No two men wanted the clicks in the same place. I myself have worked with motors that picxed up with thi ee feet of film. Where I am now, I need at least twelve feet and the extra five feet without sound. Now all this fine work will go to naught unless every manager of every theatre in the country is (Continued on Page 53) T -tv e n ty - ft time B reaches B’, A will have reached the circumference of the cir- cle. A line drawn from B’ tangent to the circle contains two points of the new wave front. If we make a con- struction similar to that at A at any point, X, on the initial wave front, we can see that A’ B’ is the envelope of all the reflected waves, and is there- fore the new wave front. Obvious- ly AB and A’ B’ make equal angles with RS and satisfy the geometrical laws of reflection. For perpendicu- lar incidence the light is reflected gack along its own path. r > pure A. O Let RS be a refracting surface, with the velocity of light in medium, I, V, in medium 2, V’. AB is a plane wave front approaching RS. Here again, if RS had not been there, aft- er an interval of time T, A would have traveled a distance VT (equal to A A’ and BB’) and the wave front would have been at A’B’. However, the ve- locity of light in medium 2 is V’, and the distance traveled by the ray strik- ing at A will be V’T. Construct a circle with A as center and radius V’T. This will represent the distance the wave from A has actually trav- eled in time T. Draw A”B’ tangent to the circle. Draw XZ the path, with re'fraction, of the ray from any point on AB. It will intersect RS at Y. Construct a circle with center Y, radius YZ times V’/V. It will be tangent to A”B’. Thus A”B’ is the new wave front. AA’ and YD show the new direction of the refracted rays. A water analogy is useful in dis- cussing interference. Suppose that two stones are dropped into a pool of water so that they set up trains of waves that have the same wave length, amplitude, and velocity. They are represented in Figure 3. Solid lines are crests of waves ; dotted lines, troughs. Wherever the crest of the wave coming from A crosses the crest of a wave coming from B we have a wave with twice the amplitude of the original waves. The same is true of the troughs. These points of intensification come in straight lines ; as CD, EF, GH, etc. In between these lines we find other lines, MN, NP, QR, etc., where trough is super- imposed on crest. Since they are of equal amplitude they cancel, and we see a line where there are no waves at all. As this happens to water waves we might expect it to happen to light as well. By ingenious devices scien- tists have accomplished this. The first was Young in 1807. He used a slit aperture and a screen pierced by T 4 A ii An Ai idh j A A ^ An Jh* iA ^ A A ifn If4ri ifA> iAi An nAn Ar rAi lAfc dlfci A earv^reetmc f v from v > / \N CV ff rejection ~yi$rt NT <$> & $ FR^EK WEAVER, Chief R-bTbABCOCK WE KOSKOFF A A Los An gcles, California J lp31 T h 1 r ty -fi i i n e GENERATOR TESTS by R. Van Slyker In testing for a ground, disconnect the output leads from the load. Take a 110 volt test lamp, or better still, a 110 volt voltmeter. Connect one leg or lead to the ungrounded or hot side of the current supply, and take the grounded side and fasten it to the frame of the generator. Touch the other lead of the voltmeter or lamp to each of the generator leads. If there is any deflection of the voltmeter or glow of the lamp, it is an indication of a ground. A voltmeter is more ac- curate in showing a partial ground, showing a feeble deflection that would pass unseen in a test lamp, due to the smaller current passing. If there is a deflection shown on the voltmeter, place pieces of paper or any other in- sulator under the brushes of the gen- erator and apply test lead to the ter- minals. If a deflection is still appar- ent the next most likely cause is that the brush holders have (due to oil and carbon dust accumulating in them) shorted to the frame. Discon- nect the leads to them and test the terminals again. If there is any de- flection of the voltmeter the trouble is in either the field coils or the brush leads themselves. Check through to the brush leads and examine them closely to see if the insulation is chafed or cracked, thus causing a ground. If these are all right cut out the field coils by disconnecting them from each other until the faulty coil is located. In the event that raising the brushes from the commutator stops any deflection of the voltmeter, it is safe to assume that the arma- ture is at fault. Take the test lead and place it against one of the com- mutator bars or segments, and rotate the armature by hand, marking the grounded bar with a grease pencil. F o r t\ Remove the armature and examine for loose binding, chafed wires, loose commutator bars or surplus solder. This routine should reveal any of the most common ills which develop in high voltage generators. Special stress should be made on the impor- tance of making each test exactly as herein directed, making very sure that no detail is overlooked since any small item overlooked will render the test false and confuse the issue. GP. *'**■* ■» T T T T * * * '» . T T T * T T V -rig] | Season’s Greetings j f j ; H. J. RILEY H. T. CRAIG j FOX ADAMS THEATRE | LOS ANGELES. CALIFORNIA 1 ► Los Angeles, 1931 j [ j ; New Year Greetings EARL LIETER FILM ARTE THEATRE Home of Foreign Pictures LOS ANGELES, CALIFORNIA, 1931 Chapter No. 7 Celebrates Second Annual Dinner-Dance and Frolic The members of California Chap- ter No. 7, together with their wives, friends and associates in the motion picture world, gathered together at the Elks Club on December 16, 1930, to celebrate their second annual din- ner dance and frolic. The occasion excited widespread attention among the celebrities of the motion picture world. Film and Stage Celebrities Present Miss Virginia Carlisle, of the M. G. M. Studio, was guest star and acting hostess to the projectionists and their guests. Mr. Gene Morgan (King of Mirth) acted as Master of Ceremonies. Mr. Morgan more than justified his title of King of Mirth on this occasion. His antics and smart cracks were a source of continual merriment. Les- ter Covan. Secretary of the Acad- emy of Motion Picture Arts and Sci- ences. occupied a conspicuous place at the guest table. Mr. H. A. Bailey, the well known local showman, was among those present. The Projec- tion Advisory Council was well rep- resented by the First Vice President, Sidney Burton (Mr. Burton is also President of Chapter No. 7. A. P. S.), and Regional Vice President, T. H. Eekerson. Dance and Entertain- ment Excellent The committee on arrangements, headed by Brother Otto Felts, who was ably assisted by Brothers C. M. Fowler and Louis Wutke, secured the cooperation of many local firms in furnishing the many features of the evening’s entertainment. National Theatre Supply Co. supplied the mu- sic by securing the services of George Stoll’s orchestra, which is one of the most popular theatre organizations. The dinner was of real banquet pro- portions and was thoroughly enjoyed by everyone. The entertainment con- sisted of several acts, which were provided by Mr. Harry Bailey, who gave generously of his time to make this part of the evening perfect. Evening Filmed The spacious banquet hall of the Elks Club was converted for a short time into a stage when lights and cameras came into play to film in sound, the event. The banquet at- tracted so many of the celebrities of the industry that the Fox Film Co., United Artists and Metro-Goldwyn- Mayer studios sent cameras, lights, sound equipment and necessary per- sonnel to record the event in cellu- loid. It is understood that the film will be used in the forthcoming is- sues of news-reels. Dance Contest An interesting event of the eve- ning was a dance contest to deter- mine the couple that excelled in the art of terpsichore. The first prize, a beautiful loving cup, was won by Mr. and Mrs. Bill DeLay. The sec- ond prize was won by Mr. and Mrs. Leonard Pyles. The loving cup and prizes were presented to the winners by the guest star, Miss Virginia Car- lisle. The party was in every way a huge success. It was one of the out- standing events of the year and was conceded to be a most enjoyable eve- ning by all present. F o r ty -one Let’s H ave Co-ordination by P. A. McGuire I have long had a persistent and enthusiastic confidence in the projec- tionist and my faith in him has been confirmed in many ways. I have seen projectionists at meetings of the American Projection Society and on many other occasions, taking an in- terest in their work and seriously dis- cussing its problems when the rest of the world, which was not attending a night club, was asleep. I have have heard projectionists on hun- dreds of occasions discussing techni- cal matters which did not affect them financially at all, and personally only through the opportunity that im- provement would present to enable them to do better work. The American Projection Society, to the best of my knowledge, was the first technical organization of the motion picture industry and has ren- dered a great service to the industry through its many discussions of the theoretical and practical problems of motion picture projection. The Society of Motion Picture En- gineers has made some efforts to en- courage interest in projection, but in- variably the only papers and discus- sions on projection have been the work of practical projectionists. I would like to go on record here and state with positiveness that I never heard any discussions on projection during the meetings of the S. M. P. E. that had any real value, that did not come from such practical projection- ists as George C. Edwards, Chauncey L. Greene, Herbert Griffin, Arthur Gray, F. H. Richardson, Lewis Town- send, Harry Rubin, etc. It is very satisfactory to observe that the S. M. P. E. seems to be making an earnest effort to put projection on a well or- ganized and systematized basis and practical projectionists are being placed on the Projection Committee. The recent activity of the Acad- emy of Motion Picture Arts and Sci- F o r t y - 1 nv o ences is particularly gratifying and splendid results are being secured through the work of Mr. Lester Cowan, manager of the Technical Bureau of the Academy of Motion Picture Arts and Sciences. Mr. Cowan has brought into this field an enthusiasm, a persistence, an under- standing and an ability to get results, which, I believe, mark a new era in the motion picture industry. It be- comes evident that we have at last realized the interdependence of the various departments of the industry and the urgent need for coordination. We now have reason to believe that the high executives of the motion pic- ture industry intend to give adequate moral and financial support to the work of the technical organizations of this industry. It is perhaps too much to hope that the industry will also give proper recognition to the work of the American Projection So- ciey and the Projection Advisory Council. These organizations have done pioneer work in the development of certain important ideas. Disin- terestedly they have worked to raise the standards of projection. I quote the following from a long article, “Let’s Have Co-ordination,” recently published in Theatre Management. “This is the day of electric enter- tainment and technicians must work to present motion pictures in the way that will be most satisfactory to pa- trons. Back of the artistic side of the motion picture industry is a vast technical field, whose work offers in- finite opportunities for flaws and failures. No single department of the technical field should be permitted to secure results with undue sacrifice of any other department. “We all have but one purpose and that is to serve the public. No in- dividual or organization has a super- iority beyond the extent to which it can contribute to the quality of mo- tion pictures as an indispensable and essential form of public entertain- ment and education. “If the technicians of this indus- try, working through their organiza- tions and with the support of the ex- ecutives of the motion picture indus- try, will work for the creation and exchange of systematized informa- tion, I feel sure that co-ordinated ac- tion can be secured, which will be of inestimable value.” There is a slowly growing realiza- tion that motion pictures are not manufactured like an automobile in a single factory, but are an assembled product passing from place to place and finally delivered to the public through those little factories — the projection rooms — away up the top and at the back of the house. Through the Projection Advisory Council we have been able to secure cooperative action along certain lines and slowly but surely are getting real results. I do not know of a single plan or idea sponsored by the Pro- jection Advisory Council, which is not the result of long and intimate contact with projectionists. It is not strange that many of the excellent ideas advanced by projectionists have not been put into effect or that the Council is not able to secure more general acceptance of its ideas. There has been a woeful failure to realize the interdependence of the various departments of the motion picture in- dustry and we are just about begin- ning to understand the urgent need for coordination. Executives of the motion picture in- dustry have been largely responsible for the failure to understand the need for discussion and coordination. They have given comparatively little as- sistance to any organizations working for the betterment of the industry. It is, of course, true that motion pic- tures were put on a commercial basis about thirty-five years ago and the art of printing is about five hundred years old. The motion picture indus- try grew like “Topsy” and much al- lowance must be made, but in these times and in this country we move rapidly and we now have a right to expect better things. Through “col- lective thought” we get organized ac- tion and the executives of the indus- try should do more to support all So- cieties and trade publications that are assisting in the campaign to improve technical standards. It is not suffi- cient to merely have technical Soci- eties of the industry as it is absolute- ly essential to have their findings and activities brought to the attention of every technical department in this field through the medium of trade and craft publications. While we are discussing the obli- gation of executives to support co- operation and coordination, it is well for projectionists to ask themselves what they are doing along these lines. Projectionists who do not take an in- terest and give some support to such organizations as the American Pro- jection Society, Projection Advisory Council and other craft organizations are not doing their full duty. Always small groups of men have been carry- ing on the work of these organiza- tions and the entire craft deriving the benefit. The following is from an article signed “Clevelander,” in a recent issue of the American Projec- tionist : “The I. A., both local and interna- tional, is primarily concerned with organization, wages, working condi- tions, rules and discipline, both as concerns ourselves, kindred crafts in the Alliance and other branches of the Federation of Labor. It is some- times argued that the I. A. should provide all this research, investiga- tion, standardization and education being undertaken by the P. A. C., and A. P. S., yet it seems clear to the writer that our International officers should not successfully be burdened with this work in addition to their already onerous duties. Were it han- dled within the I. A. separate depart- ments would have to be provided for the work with additional finances, thus gaining nothing over the pres- ent plans.” The I. A. cannot do the work of the various craft and technical organiza- tions, nor can it very well officially approve of the activities of these or- F o r ty -three ganizations. We can be assured, however, that the I. A. would soon find a way to disapprove if their ac- tivities were objectionable. All these Societies are absolutely dependent upon the individual projectionist and his Local for the practical use and development of all plans made for the improvement of projection. The American Projection Society and the Projection Advisory Council are helpless unless we receive the support of projectionists. The Academy of Motion Picture Arts and Sciences and the Society of Motion Picture Engi- neers can do little for the advance- ment of projection without the ac- tive interest of practical progressive projectionists and the work of all these organizations has a greatly re- stricted value unless the industry knows what they are doing. The trade and craft publications provide a highly effective means of keeping well informed regarding technical matters as they effect projectionists and every projectionist should sub- scribe to at least one good publica- tion. Some projectionists belong to the American Projection Society, the Pro- jection Advisory Council and the S. M. P. E., and in addition quite a few are actively cooperating with the work of the Technical Bureau of the Academy of Motion Picture Arts and Sciences. The cost of these various memberships is apparently not ex- tremely burdensome. In many in- stances it will be most practicable to belong to only one organization and subscribe to only one publication. Where projectionists, however, do not find it possible to join at least one of these organizations, there is an un- doubted obligation to see that their Local gives some kind of financial support and earnest active coopera- tion. The day of individual effort has GREETINGS! A. L. FEINSTEIN R. T. BACON R. A. OSBORNE WILSHIRf AMERICA'S MOST DISTINCTIVE THEATRE direction rnx west coAf r theatres F (j r ty - fo u r gone by. We are all part of a tre- mendous and complicated system which works for or against us. And we must utilize every effort to de- velop and protect ourselves. No man is strong enough to stand alone. Through collective thought we secure organized action, and are therefore, dependent upon various organizations to produce practical results. Let us hope that every progressive projec- tionist will associate himself in some way with the American Projection Society, Academy of Motion Picture Arts and Sciences, Society of Motion Picture Engineers and the Projection Advisory Council. If, in addition to this, the projectionist will enlarge his contact by systematic reading of trade and craft publications, backed up by a little library of good technical books, he will be in a position to do his work better today and be pre- pared for change and improvement. Progress continues ceaselessly un- der any and all conditions. For the individual or for all mankind to stand still means to go backwards. I have written about the California spirit before and am glad of this opportu- nity to observe and commend the plans that the California Chapter of the American Projection Society is making to enlarge its activities. I II Season's Greetings • : GUY WOODS ► < ; Vista Theatre - ; LOS ANGELES, CALIFORNIA, 1931 ; 3 eason s Greetings BOBBY HAMM LOUIS WUTKE LOS ANGELES, CALIFORNIA, 1931 Neic Year Greetin'? s HUGH SMITH H. BANTAU FOX-WESTLAKE THEATRE LOS ANGELES, CALIFORNIA, 1931 EG For ty -ft e (Continued from Page 21) side of the condenser, around the cir- cuit to the other side. We say the condenser becomes charged. After the condenser is charged no more cur- rent will flow in either direction as long as the voltage across it demains unchanged. If the voltage across the condenser is changed to 41 volts a current flows for an instant, and it will be in the same direction as the current flowed when the amplifier was turned on. If the voltage be lowered to 40 again the flow of cur- rent will be in the reverse direction. If the voltage is lowered still further another similar current flows for an instant. Each time the voltage across the condenser is varied a current flows, the direction depending upon whether the voltage is increased or decreased. The important point is that the current flow is through the primary of the transformer. Every time the condenser is partially charged or discharged a current flows through the primary. This is the signal.. A signal is now put into the tube. This reduces the plate current to 2.25 mils on the negative wave. 2.25 mils will not cause so great a drop in the coupling resistance as 2.5 mils did. It will produce a drop of 45 volts (.00225 times 20,000). This leaves a voltage of 45 across the plate and fila- ment of the tube, which is an increase of 5 volts. The increased voltage is also applied to the condenser, which becomes charged a little more. The charging current going from one side of the condenser, through the trans- former primary, then through the C battery, over to the filament of the first tube, to the plate, and finally back to the other side of the con- denser. We can make this more clear by redrawing Fig. 2 a couple of times, leaving out everything that does not enter into the business of charging and discharging the condenser. Fig. 3 shows the first step. The tube is represented by the resistance RP inside the circle. This is because Forty-six the path from plate to filament in the tube looks like a resistance to the rest of the circuit, and acts like one; a varying resistance. The filament in Fig. 2 is hooked to negative B, so we draw the line from the bottom of RP to point Y at the negative end of B. The top of RP goes to X, to which is also connected the coupling resist- ance R and the isolating condenser. R and the battery B are in series as they are in Fig. 2. From the con- denser we go to the transformer T, but we only show half of the trans- former, the primary. The secondary does not enter into this. We also leave out the C battery, so the wire goes from T to Y. This looks dif- ferent, but just imagine that the cir- cle is a tube, which it represents, then study Fig. 2 and Fig. 3 for a second and you will see that they are quite the same. F IG.4 Next is Fig. 4. This is exactly the same hook-up as Fig. 3. The por- tion to the right of X and Y in Fig. 3 is drawn in with dotted lines in Fig. 4, and to the left of the points X and Y. In Fig. 3 the condenser is con- nected to X. In Fig. 4 it is connect- ed to the other end of the same wire. It is still connected at a point between R and RP. In Fig. 4, Y has been slid along the wire so it now is under RP It was under B in Fig. 3. The trans- former T is again connected to Y. By another twist of the wrist we change Fig. 4 into Fig. 5. The con- denser is “slid” around from the top line to the left vertical line. Then we push the transformer down out of the way, that puts it on the bottom hori- zontal line. No changes electrically, X just drawing it differently. The bat- tery is also swung through 90 degrees and over. Now we can read all the voltages vertically, making it easier to fol- low. It can be assumed that no drop in voltage occurs in T or in B. There are 50 volts across R, 40 volts left across RP, and of course the same across C. The current is 2.5 mils. The numerals in Fig. 5 and 6 show the voltages at the points indicated by the arrows. On the negative wave of the signal the current is reduced to 2.25 mils. To make Fig. 5 conform to this new condition we must take out RP and replace it with another RP having somewhat greater resistance. Or if it is variable, increase the resistance slightly. That is more exact. It is FIG.C what happens in the tube. The new values are : R, 45 volts ; RP, 45 volts ; C, 45 volts. To explain the action when the cur- rent drops we will assume that we can break the wire between X and C just before the current falls from 2.5 to 2.25 mils. After the change RP will cause a drop of 45 volts, but C will only have 40 volts across it, due to the break between X and C. Fig. 6 ‘-hows this condition. A difference of 5 volts exists across the break. When the circuit is closed again a current must flow. The path of the current is from C through T, through RP, and back to the other side of C. This completes the circuit, and the current will flow until the voltage across C is equal to that across RP, 45 volts. The drop in current in- creased the charge on the condenser, and in doing so the charging current had to floic through T. Actually, of course, the wire can- not be opened, and the charging cur- rent starts to flow as soon as the voltage starts to rise across RP. This happens the instant the current through RP begins to decrease, and is quite gradual. When the current increases on the other half of the signal the reverse action takes place. 2.75 mils flow through RP. The drop in R becomes greater and across RP becomes less. The voltage across RP drops and as this occurs, C is discharging as long as the voltage across RP is falling. As C discharges the current is again going through T, but in the opposite direction than it did on the negative half of the wave. In this manner an alternating current is caused to flow in the transformer. Actual Occurances No. 14796 Manager buzzes fader up one — no response — another buzz and still no effect. Several buzzes more and still no louder. Manager on phone to pro- jection room says: “How come, I buzz you several times and the sound is still soft.” Projectionist ( ?) : “Its loud enough already, the monitor hurts my ears.” /• o r fy - s i ’ -t’ e n THINGS IN GENERAL by The Editor There comes a time in every pro- gressive move when either a longer or shorter stride must be taken. We have chosen the longer stride. My colleagues and I made this decision after much deliberation. We believe that the projectionists on the Pacific- slope, and all others who can be termed western, should have a pub- lication of their own. We further be- lieve that our strategic location in the immediate proximity of Hollywood, Culver City and Burbank, makes us the logical creators of such an or- gan. The western projectionist has for a great many years been considered just a little inferior by his well meaning eastern brothers. This is a reasonable assumption on their part inasmuch as the westerners have acted the proverbial part of “hiding their lights under a bushel.” In dealing with this complex as an issue to be overcome we believed that with encouragement and persistance the western projectionists could be in- duced to cast aside their shielding cloaks of modesty and show to the world, through the medium of his publication, that he is the equal of any of his fellow craftsmen any- where. Like their pioneer forebears, the western projectionists have been trail blazers. Their ideas have stolen into every phase of the industry, their originality in presentation and me- chanical operation has won for them the coveted high place they now oc- Forty •eight cupy. Upon them the industry leaned heavily during the historic transition from silent to sound pic- tures. Their response was acclaimed epical and has become a saga of the technical motion picture world. It is therefore only natural for us to pre- sume that future problems will be solved with equal dexterity and that new chapters will be written to fur- ther immortalize his fame. It is our fond hope that this magazine will be allowed to record each month the steps of his progress. To this man, THE WESTERN PROJECTIONIST, wherever he may be located, we pledge our efforts and the support of this magazine un- stintingly. i i i Monthly Health Hints Don’t touch a high voltage con- denser for at least five minutes after disconnecting it. ❖ ❖ ❖ Your rectifier transformer is very potent to the touch. Lay off! ^ ^ ^ Never wash your mouth or teeth with your battery syringe. He Hi * Don’t use a hydrometer for a fever thermometer. It might cause your tonsils to fall out. ❖ ❖ Don’t use Vitaphone needles for toothpicks. Hi Hi Hi Film cement does not mix well with Silver Fizz. Hi Hi Hi Never go to sleep in a Super-Hi Lamp house. Willard Bridges, chief at United Artists, has returned from New York, where he supervised the opening of “The Bat Whispers” for the new United Artists wide screen picture. They call it Magnafilm. That go-getter that goes and gets, none other than Brother H. C. St. Clair, has started his regular annual auto license getting debauch. See h'm about your new license, NOW! But don’t forget, you can’t all have number seven. Why doesn’t somebody write in some of the doings of the brothers so that we can make these Pin Spots HOT!!! Brothers Young and Borch have been extremely busy installing a wide screen, new lamps, etc., at their cin- ema emporium in Huntington Park. Crusoe and Friday Bill : Hello, Chuck. Have you seen Harry Perriseau? Chuck: No, but I just saw Doc Prestons coat tails going around the corner. Hurry and you can catch them. Brother Wallace Maxon, not con- tent with seeing half the towns in the United States, journey with the Mrs. to Agua Caliente. We strongly sus- pect that the prime moving impulse was the desire to escape the arid cli- mate of the home town. Brother Jack Helm is now at the Columbia Studio, having been select- ed by Bro. Howard Edgar to fill a recent vacancy. FROM OAKLAND, CALIFORNIA Charlie Ball’s latest inventive ef- forts are pushing him toward a per- fect “Fader.” We are told that a per- fect fader automatically goes up on the right side. Charlie says he will accept suggestions. Joe Carter’s favorite outdoor sport is catching big fish then having to jump in after them. A1 “Putts” Paxton is the only chief in Oakland, he has a hat that proves it. Bill Rose said he wouldn’t have it “Infra-Red” because he doesn’t know him. Dan O’Brien has the number of all our golf players, his latest cartoon proves it. Geo. Lancaster discovered that put- ting the fuses in upside down will not make the motors run backward. Bill Rose says an automatic “fader” is A1 Nagle, who always has his dough on the line. F o r ty - n i n e oings California Chapter Number Seven The new year starts with a hang! At our first meeting in the new year we are to he the guests of Mr. C. A. Ashcraft, who is well known to all projectionists as the manufacturer of the famous Ashcraft Automatic Arc. Mr. Ashcraft has arranged for our entertainment in his establishment at 4214 Santa Monica Boulevard. Lunch will be served, after which Mr. Ashcraft will explain the proper method of maintaining and operating the new Super H I intensity lamps which he has de- veloped for use with grandeur, magnascope or any of the wide screen systems. Mr. Ashcraft’s skill as a lecturer and host is well known, so no member will want to miss this lecture. Remember the date and address. Tues- day, January 6, 1931, 12:00 midnight, at Mr. Ash- craft’s factory, 4214 Santa Monica Boulevard, Los Angeles, California. The second meeting of January will be held at the T. V. G. Building, 936 West Washington Boulevard, at 12:00 midnight, Tuesday, January 13, 1931. Lunch will be served (the first by the new committee), after which we will hear an educational lecture. ALL MEMBERS ARE SINCERELY URGED TO BE PRESENT F i ft y A A A A A ■JL.M. Words alone will not suffice in showing, nor can they begin to ex- press the appreciation felt by me in having the honor of Secretaryship of the American Projection Society, Chapter No. 7, bestowed upon me, a comparatively new member. I fully realize the precedent established by Brother Koskoff in the able fulfill- ment of the duties of this office, and I shall, to the utmost of my ability endeavor to follow the splendid ex- ample set forth by him. Fred L. Borch. Retiring Secretary’s Greetings The opportunity of greeting and extending good wishes to my success- or becomes an easy task. The new secretary of Chapter No. 7, Fred L. Borch, being one of the most capable and willing men available, the con- tinued growth of the organization is assured. The office of secretary is difficult and the interest of the selected man in his work reflects directly on the forward strides of the Society. Exceedingly favorable comments from various corners of the country on our phenomenal growth, success- ful work and active interest in pro- jection and its affiliated problems of sound, optics and general showman- ship would not have been forthcom- ing if the body at large were not one hundred per cent for their officers. My best wishes and sincere hopes are that California Chapter No. 7 con- tinues to grow. I know that if the membership will support its new of- ficers, cooperate with Fred Borch, as they have cooperated with me. For had I not had their support and confi- dence I couldn’t point with pride to a two and a half year record of won- derful association. For this I am truly thankful. The personal interest I have taken is evidence that A. P. S. men have fidence in our new secretary, that I am asking for and wishing Fred Borch a definitely successful term in the important office of secretary, California Chapter No. 7, American Projection Society. David Koskoff. F i ft y - o n e Criterion Theatre EXTENDS Reason's (Srcctinas LEONARD PYLES T. E. DE LAY W. W. WELLS OTTO FELTS F if t y - 1 w o Standard Release Print Continued from page 25 also held liable with the projectionist to see that this is not ruined. I have worked in two Fox Theatres where the managers would try every conniving meth- od to kid the audience with trailers. They would order us to put these trailers n such places that we would have to cut the leaders or run out in order to get over their pet schemes. Some of these theatre circuits will have to teach their managers how to put up a show. I think it would be a good idea if such men as Oldknow and Arthur of Fox were put wise to some of the methods used by their managers. In some Fox Theatres they split the news to put a trailer in the middle of it. In the theatre where I am now all advertising is done either in front or behind the News. So the News is run solid. The Projection Advisory Council will have its hands full to put this “Standard Release Print” over in the theatres. So don’t overlook the fact that you have men in the shape of managers to deal with who are more ignorant than many (operators). I would like to see all advertising kept in one spot in the program and have it ail together. If we must cut leaders and run-outs, let it be the News. Some of the Shorts I get today are as bad as when I was in that dump in Jamaica. They are awful. Only yesterday the manager wanted to know why some of the < omedy was cut. He missed some of it. My partner was the one who started the motor oil ihe first click when he should have started on the third and he was forced to change over be- foi e the reel ran out. He had some time ex- plaining to the manager just how it all hap- pened. .More power to you. Me; you have a big job °n your hands and nobody knows it more than I do. With best wishes for your success, I am. Cordially vours, (Signed) W. C. BUDdE. 1. A. T. S. H. & M. P. M. O. Local 525 P. O. Box 525, Aberdeen, South Dakota, November 8, 1930. Projection Advisory Council. I, am" ee Junes, Secretary, Box !is. General Post Office New York. N. V. Dear Sir and Brother: Pitts will acknowledge receipt of vour booklet, “Standard Releast Print Makeup and Practice.” We note with interest and gratitude that nu- merous evi.s confronting the projectionist have keen done away with. It is useless to state here what a benefit a standard nomenclature will lie to the industry and this can only be appreciated after the projectionists throughout the country have been convinced of the feasibility of this pla n. I hanking you sincerely and assuring vou of our co-operation in making this well known among the members, we remain, LOCAL, 525, I. A. T. S. E. — M P M O (Signed) R. W. MERRIFIELD, Sec’y'. It will be a real pleasure to print any letters received on this subject. Only in this manner can you let the Projection Advisory Council and the Academy of Motion Picture Arts and Sciences have a true version of the success of the system in the field under your supervision. Write to the editor of the Loudspeaker. Thoughts While Stalling Apologies to O. O. McIntyre I wonder who puts in all the green back-patches. , . It was a great din- ner dance, it Otto be. . . Who fur- nishes Fred Weaver's hair tonic? . . . And who trims Dave’s mustachio? . . . All the conveniences of home in Perry’s new layout for the Gumbiner Theatre. . . When is Connie going to furnish roller skates for his crew? . . . The man who writes the best articles is also the most modest and retiring, he is J. R. G., of Oakland, Calif. . . Jerry Knowles’ new rear shutter for Motiographs do every- thing but milk the cow. . . Our choice for Beau Brummel of the A. P. S. is Bill DeLay, ROY!!! but he looks slick in a tux. . . The most perfect choice of the recent election — Frank Mc- Bryde, sergeant-at-arms, what prow- ess. . . Who designed the old type fader most of us use? . . . Why don’t we hear from Art Negley? He must have lost his fountain pen. . . Jimmie Lucas should have been a traveling salesman, lots of jumps. . . Ouch! my operation !!!!... Our choice for after dinner speaker par excellent. Rro. Frank Seavier, of San Francisco. . . Wait a minute. I've got to make a change over. . . Back again. . . I won- der if Adolph Menjou knows he looks like Pop Kenton, especially the mus- tache. . . You’re probably disgusted with this line by now. . . So am I. ‘-D’.i f'ty - t h r e e San Francisco Chapter No. 17 Elects New Officers The following officers have been unanimously elected to serve for the year 1931 : President — Frank L. Seavier. Board of Governors — Harry C. Everett, Vice President; Frank Cos- tello; Paul 0. Gaffney. Treasurer — Walter G. Reinhardt. Secretary — John Ford, Jr. Sergeant-at-arms — A. E. Murray. i i i A projectionist in a restaurant or- dered steak and received it rare — too rare. The ensuing conversation fol- lowed : “Waiter, take this steak back and have it cooked.’’ “ 'Tis cooked,” snapped the waiter. Projectionist: “Like heck it is. I’ve seen cows hurt worse than this and get well.” Dinner- Da nee Celebration Local No. 306, N. y. A dinner and dance in celebration of the 17th anniversary of Local 308, M. P. Projectionists’ Union, will be held Jan. 17 in the grand ballroom cf the Hotel Astor. Sam Kaplan, presi- dent of the organization, is chairman of the committee. New Year Greetings GOLDEN GATE THEATRE K. GRAHAM R. FLETCHER Los Angeles, 1931 77 if ty -f o u r 5> '.tel BL ! SEASON’S GREETINGS ■ •> [ from Reason : [ .% >•* v v v Af' f ♦ [ ^(©reetmas ; | EMBASSY ► .T . . • THEATRE : LOYD C. LITTON : l Robert G. Haines, Mgr. t CHAS. PL BALL Jr. ► WILLIAM E. ROSE ► Henry A. Schelf, Asst. Mgr. : JAMES B. PERRY [ Jules R. Pfau, Projectionist GEORGE F. DYER | m BEN P. GILLARD ; ; JAMES B. GILLARD | Los Angeles, 1931 [ | Officers Chapter ? 12 : | Oakland, California : ] ^ ^ ^ ^ ^ ® • 'tel gi- HARRY CAGE New Tear Greetings EL PORTAL THEATRE LOS ANGELES, CALIFORNIA 1931 B' Season’s Greetings from TEX LESTER irfe, 3^. Los Angeles, 1931 97 ///>' • /V -X'l? 'X'rtu Rear ($rcetinys From jWulticolor laboratory SYCAMORE and ROMAINE HOLLYWOOD, CALIFORNIA Sidney Burton Supervisor of Projection to American Projection Society Chapter Number ^Severn Printers and Publishers 435 WestV crnon Avenue, Los Angeles Telephone O ,T\ ridge 1522 <£i ®. Congratulations to the American Projection Society Chapter Seven Progress made by any organization denotes the quality of the men behind it. Our greatest aim is to be known as the most progressive manufac- turers of : SUPER HIGH INTENSITY PROJECTION ARCS HIGH INTENSITY REFLECTOR ARCS LOW INTENSITY LAMPS • cUliI • ACCESSORIES FOR PROJECTION ROOMS Ashcraft Automatic Arc Company 4 2 14 SANTA MONICA B O U L E V A R D i f ty -e i c h t 5^ The Best H. I. Combination Ashcraft Lamps . . . BIO CARBONS Ve dare say that 99% of the members of the A. P. S. will agree that the best high intensity results are secured with RIO car- bons. Breck Photoplay Supply Co. Distributors of: RIO CARBONS ASHCRAFT LAMPS CINEPHOR LENSES SUPER-CINEPHOR LENSES SUPERLITE LENSES DA-TONE SOUND SCREENS KAPLAN PROJECTORS ROTH MOTOR GENERATORS MOON REWINDS WEAVER DOUSERS 1909 South Vermont Avenue • Los Angeles ——a S7 i fty- h i n e Season’s Greetings Theatre Engineering Service Co. 1442 Beachwood Drive Hollywood, Calif. JAS. J. GRAHAM A. P.S. No. 7 CHAS. C. REESE A. P.S. No. 7 “Building Theatre Patronage” By JOHN F. BARRY and EPES W. SARGENT Extracts Reprinted by permission Chalmers Publishing Company, New York BETTER PROJECTION PAYS TO-DAY audiences know good projection. They may not use technical terms in discussing it, but they do discuss it. They may not walk out on poor pro- jection, hut they avoid the theatre where it is permitted. GOOD PROJECTION IN MANY CASES IS THE DECIDING ELEMENT WHICH DETERMINES PATRONAGE AT A THEATRE RESPONSIBILITY The theatre manager may not be responsible for the theatre site, for the quality of productions booked, for the equipment and decoration of the house, or even for the extent of advertising which is limited by an exacting advertising budget. But projection is something for which he is responsible. He cannot be efficient if he cannot supervise projection. There are instances where managers spend time com- plaining about the quality of photoplays available, when projection at their theatres is so defective that discriminating patrons would avoid the theatre no matter what was on the program. Good projection is demanded to-day from everyone — from execu- tives at the studio who know that poor projection can ruin a good photoplay, right down to the patrons at the theatre. IMPORTANCE Why is projection important? The very nature of motion-picture entertainment makes it so. During such entertainment patrons like to feel that they are part of the story, living the action — moving, fighting, fearing, thrilling; moving on and con- quering with the characters on the screen. Thus they live what might be called an “illusion.” They are carried away to the scene of the action, or, better still, find themselves right in the action. This illusion makes entertainment satisfactory. It cannot be satisfactory if something happens to spoil the illusion — something that re- minds the patron that he or she is sitting in a theatre chair looking at a two-dimen- sional surface covered with light and shadow. Defective projection prevents the patron from slipping right into the story, and living through it with the characters. Defective projection can jerk the patron right out of the action of the story and spoil the illusion that is being lived through. DEFECTIVE PROJECTION CAN MAKE SATISFACTORY ENTERTAINMENT IMPOSSIBLE How necessary for entertainment is this illusion which depends so much upon projection is evident by comparisons. When you read a novel, your entertainment is satisfactory if you forget that you are reading print on pages. The skill of the novelist takes you right into the action, and against the background of the story you live through the action with the characters. An illusion is created. If, while you are reading, someone slams a door or disturbs you in some other way, the illusion is spoiled and you are jerked back to realize that you are just sitting in a chair with a book in your hand. The entertainment is spoiled. The same thing happens if the print is poor, if the lighting is defective, if the chair is uncomfortable. At the motion-picture theatre, entertainment depends upon an illusion which is created by many, 1113113- details. But projection is one of the most important. Any one of a hundred small or seemingh- small defects in the projector or the screen, or small mistakes byr the projectionist, can spoil all that was done b}r the scenario writer, the director, the cast, and the long line of h ighly- paid artists and experts whose genius was spent in the preparation of the film. A nois>' machine, dust or oil on the lens, warped film, a bent sprocket, vibrations of the projector, careless change- overs, improper speed, a dirty screen, a carelessh' fitted screen — these are but a few of the causes that can spoil what patrons pa>' to get and what high-salaried talent labored to produce — satisfactory entertainment. FOR BETTER PROJECTION Simplex the international projector The International Projector Corporation : 90 Gold Street, New York HE RIGHT EQUIPMENT CORRECTLY • INSTALLED 4 4 4 4 4 Switchboards 1 i Theatre Lighting Fixtures Scenery and Draperies Stage Rigging 4 i Stage Lighting Devices j Projector Carbons i Mazda Lamps Lobby Frames j Theatre Signs and Marquees j 4 4 4 41 41 4; 4 National Theatre Supply Co. i i Offices in All Principal Cities * i SIS By DR. LESTER E. REUKEMA ' '0$ k ' ' jf ',. 1JMSK .3yp " A i Twenty-five Cents CENTRAL — each backed by a great national organization al- ways at your service CHICAGO. ILL. 825 S. Wabash Ave. CINCINNATI, O. 1635 Central Parkway CLEVELAND, O. 2172 Payne Ave. DENVER, COLO. 2106 Broadway. DETROIT, MICH. 214 W. Montcalm St. INDIANAPOLIS, INK. 434 N. Illinois St. KANSAS CITY, MO. 108 W. 18th St. MILWAUKEE, WIS. 719 Wells St. MINNEA POLLS, M I NX. 56 Glenwood Ave. OMAHA, NEB. 1510 Davenport St. ST. LOUIS, MO. 3210 Olive St. EASTERN ORDER FROM OR MAKE INQUIRY AT YOUR NEAR- EST NATIONAL BRANCH —SEE LIST BALTIMORE, MD. 309 N. Gay St. BOSTON MASS. 211 Columbus Ave. BUFFALO, N. Y. 376 Pearl St. NEW HAVEN, CONN. 133 Meadow St. NEW YORK, N. Y. 1560 Broadway PHILADELPHIA, PA. 1315 Vine St. PITTSBURG, PA. 1006 Forbes St. WASHINGTON. D. C. 916 G. St. N. W., Room 513-15-17 Mather If It’s for Use in the Theatre, National Can Supply It. SOUTHERN ATLANTA, GA. 187 Walton St. CHARLOTTE. N. C. 222 West Fourth St. DALLAS, TEXAS 306 S. Harwood St. MEMPHIS, TENN. 400 S. Second St. NEW ORLEANS, LA. 220 S. Liberty St. OKLAHOMA CITY, Okla. 516 W. Grand Ave. WESTERN LOS ANGELES, CALIF. 1961 S. Vermont Ave. PORTLAND, ORE. 460 Glisan St. SALT LAKE CITY, Utah 248 E. First South St. SAN FRANCISCO, CAL. 121 Golden Gate Ave. SEATTLE, WASH. 1st Ave. and Battery St. National Theatre Supply Co. Executive Offices--92-94-96 Gold Street, New York -0 EDDIE HARRIS Asks — "Are YOU Interested In A WELDED Film Splice — or — Does JUST A PATCH Satisfy You?" Our Slogan: "The Splice is Stronger Than the Film Itself." is not merely a "catch-word" — It means that the break in the film is ACTUALLY welded as steel is welded — FOR PERMANENCY! ; We feel, at this time, that an analysis of the working of ODORLESS — FLAMEPROOF — 2 in 1 FILM CEMENT and the 1 ordinary QUICK DRYIXO cements on the market, will clear up [ a mis-understanding as to the value of a quick drying cement and ■ one of less volatility. 1 To WELD a break you must FUSE and M ELT the broken pieces h into each other to become ONE. To PATCH a break you just use an adhesive to make TW O SURFACES stick to each other ; FOR THE TIME BLIND — They will come apart — in the case of film, ether will do that. I Ether being highly volatile, dries quick, hence can only get a ; surface grip on the film and soon opens ! i ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT having ' low volatility evaporates slower BUT melts and limes the broken . film into a WHOLE. A Film Splice made with 2 in 1 will STICK IMMEDIA1ELX but WILL NOT stand an immediate PULLING TEST. MAKE YOUR SPLICE-REEL YOUR FILM IN CONFIDENCE— AND FORGET IT! It’s $1.25 a Pint Parcel Post Also Makers of Truevision Parts, Fire X Liquid, Lens Paste, Rust Remover, Gum Remover, Perfumes, Etc. i 2 CEMENTS INCORPORATED INTO 1 FOR USE ON SAFETY AND i REGULAR FILMS Hew es-Gotham Co. B- — iS U n e 520 W. 47th St. New York “Building Theatre Patronage” By JOHN F. BARRY and EPES W. SARGENT Extracts Reprinted bx permission Chalmers Publishing Company , 'New York BETTER PROJECTION PAYS SUPERVISION The quality of projection depends in some way upon the manager’s super- vision. He is responsible for evert' detail of operation, and this includes pro- jection. This does not imply that the manager should be blundering and interfering with the projectionist. The manager who tries to interfere without knowing what it is all about, is just as much at fault as the ignorant, over- cautious manager who lets projection go on without any supervision because he is afraid to speak. The ideal condition exists when the theatre manager is familiar with the problems and can talk the language of the projectionist —and when the projectionist, taking real pride in his work, desirous of putting the best possible projection in the same at the least possible cost, is capable and conscientious and thoroughly interested in the welfare of the theatre. Then the manager and the projectionist can discuss common problems, each confi- dent in the practical common sense and the interest of the other. Poor pro- jection has put theatres out of business and in many cases it was often some- one else and not the projectionist who was responsible. PROJECTIONISTS Incapable projectionists are rapidly dropping out of the business and their places are being taken by men with the professional attitude. These men expect the manager to be appreciative of projection problems, to be familiar with equipment needs, to be co-operative, and to supervise projection intelli- gently. The capable projectionist is not a mechanical worker whose duties are limited to loading the projector, and later placing the film back into the can. He is constantly improving his knowledge, interested in principles of electricity, heat, optics, lenses, light-and-shadow effects, photography and light mediums. He is familiar with the almost countless parts of the very delicate mechanism and he is using inflammable material which, when carelessly handled, can do untold damage and cause needless expense. Knowing the naturalness of moving objects, he can give the proper speed for the scenes requiring speeding up, and scenes requiring slowing down. In other words, the efficient projectionist is to be respected. He is a real asset in any theatre. His interest in his work and his desire to improve often depends upon the attitude of the manager. Consequently, it is no exaggeration to say that projection in the theatre often depends upon the manager’s tactful, sympa- thetic, encouraging common-sense handling of the projectionist. INFORMATION If the manager is properly informed, many economies can be practiced and projection can be properly supervised. The manager who can distinguish good projection from bad projection, watching it from different positions in the house, can help the projectionist whose opinion is based on what he sees only from the porthole of the projection room. When defects are noticed, inquiry should be made into the cause of the defect and provision made so that it will not happen again. ECONOMIES CARELESS MAINTENANCE OF EQUIPMENT IS THE CAUSE OF MANY WASTED DOLLARS. PARTS SHOULD BE ORDERED LONG ENOUGH IN ADVANCE TO PREVENT EMERGENCIES AND TO SAVE THE EXPENSE ENTAILED BY TELEGRAMS. CONCLUSION As far as the manager is concerned, good projection depends upon three things: Technical knowledge, good business sense, and a personality that will develop the proper relationship with the projectionist. All three are essential. Intelligent superivsion will be difficult unless there exists a spirit of co-opera- tion and mutual understanding between the manager and the projectionist. FOR BETTER PROJECTION Simplex the international projector The International Projector Corporation : 90 Gold Street, New York Earning the confidence of an industry... v Weaver Bros. Manufacturing Co. LOS ANGELES, CALIFORNIA Manufacturers of Wea ver Auto Douser Distributed by National Theater Supply Co. Weaver Curtain Control Distributed by Armstrong Power Co. L_ Thret In memory of our departed Union Brother WILLIAM M. FELLOWS Local 150, I. A. T. S. E. A Technical and Educational Publication. Devoted to the Western Projectionist and his Prog ressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G. CROWLEY H. E. ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE 1264 Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Phone II25W Circulation Volume II. FEBRUARY, 1931 Number 2 CONTENTS How to Study By Dr. Lester E. Reukema 7 Ashcraft Air Blast Arc Lamp 9 Regulating Density of Sound Track By H. C. Silent 13 Just How Clever Are You? 16 Standard Release Print Comments 17 Craft Technical Data By A. C. Schroeder .... 19 P. A. C. Activities in San Francisco Bay District 24 Horns and Speaker Units By D. B. McGown ... 26 Things in General By the Editor 28 Pin Spots 29 Chapter Doings 30 Secretarial Comments 31 Caesium Cell By Harold Swanson 36 Published Monthly by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. In Groups of Five or More, $1.00. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager. 2628 West Blvd., Los Angeles. California • .7,' • 9 Typical Scenes at Chapter Seven’s Dinner Dance Left to right — Mr. Wallace J. Maxon, Mr. .Tames Pointner, Mrs. James Pointner, Mr. Gerald Knowles, Mrs. Gerald Knowles Left to right — Mr. William Delay, Miss Pheobe Lanby, Miss Virginia Carlisle, Mrs. Leonard Pyles, Mr. Leonard Pyles "HOW TO STUDY” By DR. LESTER E. REUKEMA Professor of Electrical Engineering, University of California, Berkeley. ACCOMPLISHING ART OF CONCENTRATION ESSENTIAL » » » For thousands of years in the his- tory of the human race, education was a prized opportunity reserved for an exceedingly limited minority. The man who could read and write was an exception, books were so expen- sive and so limited in number that they were available only to the rich, and the working day was so long that only the leisure class had any time for study. Even today this condition exists in many countries of the world. Fortunately, however, education in our own country, and particularly in California, is available to everyone who wants it and is willing to exert a little effort to get it. Wages have increased until we can all afford to buy books and public libraries make them available to those who do not wish to buy them. Working hours have decreased until we now all be- long to a more or less leisure class. We all have the time and the oppor- tunity to study. Because education is so easy to obtain, however, because every one who wishes it can have it. we are likely to overlook the fact that education is just as much an oppor- tunity to be grasped and valued now as it was when it was so rare and so difficult to obtain. In fact, an educa- tion is more necessary now than ever before. The more universal educa- By L. E. Reukema, A. P. S., tion becomes, the more handicapped is the man without it. And the han- dicap is of his own volition. Except in very exceptional cases, he is de- feated because of his lack of ambi- tion. It is easier to idle his time away during his leisure hours than it is to study. If he does start to study he gets descou raged before he has made an honest effort, or perhaps he just puts off studying as something which can be done just as well next week or next year. He excuses himself by saying that he never had a chance, that his early education was neglect- ed, that lectures or books which his fellows are studying are over his head. It would be well for all of us to read the lives of men like Lincoln or Pupin, and see how the will to succeed and to accomplish something worth while can surmount any handicap. Picture Lincoln as a boy, limited to a formal education of only a few months each winter in a single-room S e X' e n school-house in the back woods, miles from his home, working his problems with charcoal on the back of a shovel by the light from a fireplace, trudging miles after a long hard day’s work to borrow a book from a well-to-do neighbor, yet by his own efforts pre- paring himself to assume the highest position possible to attain in our coun- try and to so shoulder up to his re- sponsibilities that his name is re- vered today throughout the world. Picture Pupin, a peasant boy of Ser- bia, fired with ambition by hearing the story of Lincoln, working his way to America, the land of opportunity, educating himself until he became a power in his adopted country, a keen, clear thinker, one of our foremost educators, scientists, and inventors. A PLAN OF STUDY IS NECESSARY Study, to be truly effective, should be organized. To merely play at studying, reading in a more or less hit-or-miss fashion, when the fancy strikes one, now on one subject now on another, never really getting at the fundamentals of anything, never test- ing one’s understanding of what has been read, will not get one very far. When a wise man wishes to save his money, he does not spend money first for whatever strikes his fancy, then save whatever is left. There will sel- dom be any left. Rather he plans carefully how to get the most value for money spent, and so budgets his income, no matter how small, as to include a substantial part for saving and careful investment. A wise man also budgets his time, so arranging his hours that he can spend at least a few hours each week in developing his abilities, in studying something- worthwhile. Time so spent pays high dividends, both in money and in en- joyment. If possible, join some group inter- ested in and studying the same sub- jects as yourself. Such competitive study keeps up interest ancT gives one the opportunity of discussing the sub- jects studied and of hearing the viewpoints of others. E ight EFFORT IS NECESSARY In studying, there is no substitute for personal effort. What we get out of anything depends largely upon what we put into it. Every worth- while thing in life demands a price and it would be queer if wisdom, the most worthwhile of all, could be ob- tained without a struggle. The help of a good teacher usually enables one tc learn faster, but the best teacher is the one who shows his students how they can solve their problems without his help, who teaches them to be self re'iant. Such a teacher de- velops leaders, who assume respon- sibilities confidently, who think for themselves. To succeed in anything, whether it be sport, art, business, or anything else requires sustained effort, con- centration, a stiff upper lip when things seem hard, good sportsman- ship. A quitter never gets very far, and the man who merely plays at the game but shirks the hard work never makes the team. Notice the swim- mers next time you go to the beach. Most of them merely play in the wa- ter, never swimming more than a hundred feet at a time, using strokes which waste half their energy in beat- ing the water. Many of them have been playing at swimming for years and they never will be able to swim any better than they do now. To learn to swim well requires concentration, sustained effort, mastering the fun- damentals one after the other. It involves studying the methods of others who are successful, then prac- ticing these methods until they be- come second nature and can be done without thinking. Is the effort worth while? Who in the end gets most fun out of swimming, the one who can propel himself speedily through the water apparently without effort for long distances, whose every movement is graceful, who can take care of him- self in the roughest water, who can save a life in an emergency, all be- cause he was willing to pay the price (Continued on Page 22) Ashcraft Air Blast Arc Lamp Successfully Demonstrated Many New and Revelutionary Features Used » » » Every projectionist is aware of the fact that the high intensity reflector arc, of all lamps used for projection work, is the most undependable. It is only within the last three years that attempts have been made to popularize this type of lamp. Within that time no radical changes or im- provements have been made. The first types of high intensity re- flector arcs were non-rotating and practically an adaptation of the high intensity principles to the low intens- ity reflector arc. This method was found exceedingly unsatisfactory. First, for the reason that it is abso- lutely essential to rotate the positive carbon in order to maintain a picture free from discoloration. In the sec- ond place, the mirrors were of insuffi- cient distance away to prevent their breakage and deterioration of the in- tense heat of the high intensity cra- ter. Heretofore, every high intensity reflector lamp was practically the same, and its defects have been a nightmare to the projectionist. When the word “arc lamp’’ is men- tioned, immediately the thought of a burned, oxidized and black mechan- ism covered with ash and soot is called to mind. Only with the great- est difficulty has it been possible to keep the working parts of previous arc lamps properly lubricated, and this was necessarily done with spe- cial lubricant able to withstand high temperatures. Manufacturers have evidently had it in mind that in order to secure the maximum efficiency from this type of lamp that it was absolutely necessary to cut the projected image of the element itself to the minimum. By so doing, mechanical strength was sacrificed to such an extent that the lamp was quite undependable. It has been quite a problem for the projectionist to learn the method of changing carbons in his lamp in such a manner that he would not be liable to burn and blister his hands, the usual method being with pliers and screw drivers, great pains being taken not to touch the carbons at any point. Perhaps the greatest fault to be found with the ordinary high inten- sity reflector arc is the present meth- od of conducting the current to the positive rotating carbon. This method N i n e is stereotyped in all lamps and con- sists of two blocks of metal clamped to the carbon by a spring. Every day, some times twice a day, it was necessary to remove these blocks of metal and file or scrape their surfaces to remove the oxidized metal. Some times during this operation the cur- rent -carrying leads would break oft' and many times screws were twisted off, making it necessary to dash madly to a machine shop to have the broken parts removed. Besides be- ing of great annoyance the replace- ment of these contacts and leads was exceedingly expensive. Method of Eliminating Defects All of these defects were recognized by the Ashcraft Automatic Arc Co. and every attempt has been made to eliminate these faults. The job has worked out beyond our expectations and as a result we are placing on the market immediately the Ashcraft Air-cooled High Intensity Reflector Lamp. In this machine, perhaps the first lamp which can be termed a ma- chine, the heat has been localized at the carbon tips. Every working part of this lamp, including contact shoes, carbon feeding mechanism, bearings, shafts and gearing, as well as all the current-carrying leads are entirely inclosed. The burner consists of three parts : Positive assembly, negative assembly and the inclosed bed-plate. The bed- plate carries underneath all of the re- duction gearing as well as the mech- anism for throwing off the automatic feed and applying the manual opera- tion. Each of the bearings carrying these gears and shafts is provided with suitable oil cups. The gears themselves are lubricated with grease or vaseline . Every gear contained in the mechanism is of steel, hard- ened and ground. Those gears which are spiral are provided in the thrust ends with ball bearing thrust bear- ings. Air Cooling Described Upon this bed-plate is mounted the positive and negative assemblies. The forced draft of air passes through a duct located on the lower ‘ Ten part of the housing base and passes into the inclosed bed-plate where it keeps bearing, gears and lubricant cool. It then passes through the positive and negative assemblies. In passing through the positive assem- bly, the action is entirely vertical and passes over the contact shoes, the feeding mechanism, the ball bearing, keeping these parts sufficiently cool to touch at any time, no matter how long the lamp has been in operation. By keeping these parts cool it also cools the positive electrode the en- tire length except for that part which projects beyond the baffle plate. In this manner the carbon is prevented from oxidizing and deteriorating within, thus allowing the passage of a great deal more current than was formerly possible. This air draft in passing through the negative assembly cools the bear- ings and leads located within and passes to the rear of the reflecting mirror which it cools to an appre- ciable extent. The air draft passing through the positive assembly escapes at the top through a suitable vent and is of sufficient force to blow the ash generated by the arc out of the lamphouse vent. It will be found that very little, if any, ash or deposit is left within the housing. Increased Current Capacity With the ordinary high intensity reflector lamp it is impossible to sub- ject the positive electrode to a cur- rent in excess of 75 amps. With this lamp 85 amps, is normal — not the maximum by any means. The high intensity reflector arcs have been very limited in their range of feeds for various currents, it being found that above 72 amps, it was practically impossible to operate the motor at sufficient speed to keep the carbon in the proper position. We have allowed leeway both ways on this new lamp. The operator will find that while the control mechanism is sensitive it is also easy to set in the proper posi- tion. It is difficult to realize the exces- sive amount of light generated by the addition of 10 amps, to the 9 mm. electrode, but we can say that the light generated by this lamp is suit- able for the projection of the picture 40 to 45 feet in width. Our only instructions to projection- ists in properly caring for this lamp are that it be oiled weekly at those points provided. As far as contact shoes are concerned the projectionist may forget this point entirely. We do not anticipate that at any time these will demand attention. Equalized Double Contacts The type of positive electrode con- tact used in this lamp is absolutely new. Instead of using the usual two contacts we use four, two on each side of the electrode. Those four contacts are equalized in such a manner that the full three-quarter inch surface of each contact will bear evenly on the carbon. The contact area has been doubled and so designed that the max- imum of area is presented to the air blast. The total length of contact is thi'ee inches. The rear contacts never get hot. To the front ones is nat- urally conducted a certain amount of the heat from the carbon itself, but this heat is rapidly dissipated into the air draft. We find that the for- ward contacts do not burn, but their surfaces may become discolored from the action of the heat. This is abso- lutely unobjectionable and in no case except that where actual pits are dis- covered should an abrasive be used upon them. The polished color sur- face is highly desirable and a re- moval of this color is of no way a benefit. The usual dowser is placed between the arcs and the reflecting mirror, but we find that it is practically un- necessary as during a considerable period of time the arc has been started and operated without using this unit. We do not find that the mirror suffered in any way, no par- ticles being visible upon its surface. The only time we advise using the dowser itself is when burning the crater in a new trim. At this time there is a possibility of a certain amount of smoke shooting out upon the surface of the mirror. The foregoing points we think will eliminate entirely the faults usually found in high intensity reflector arcs. We also feel that we are giving to the industry a lamp which can be cared for the same as a projector mechanism. It is mechanically strong, and at no time may the projectionist anticipate a break-down during op- eration. The Arc Control Regarding the operation of the arc control we have found it advisable to design this as an entirely separate unit, locating it upon the mounting rods projecting from the side of the E l c ■ v e n lamphouse. The motor now used is two and a half times as strong as that previously used, and has a range of speed of from 1800 to 3800 rpm, suf- ficient to accommodate any range of carbon consumption. The gearing from the motor to the drive shaft is, like the element gearing itself, steel and heat-treated. Independent Feed Control The forward feed of the positive electrode is regulated by the speed of the motor which is controlled by the rheostat located within the arc con- troller case. This is so flexible, that no difficulty will be encountered in its setting or maintenance. The negative feed is entirely independent and is also regulated by an adjustment lo- cated within the arc controller case. Nine different steps are provided which will accommodate a current range of from 68 to 90 amps., each step indicating a forward increase ot speed in the negative electrode of ap- proximately .003 of an inch. There are seven bearings within this arc control, each one provided with an oil hole. All the shafts used in this mem- ber are drill steel, exceedingly tough. These, operating in the cast iron bearings, will give long life to all working parts. The feed of the nega- tive carbon is intermittent, the mo- tion of the driving gears being inter- rupted from time to time by a cam action. All these motions are very slow and any wear occurring on these parts is of no consequence. Unit Construction The blower providing the forced draft of air is located on the driv- ing motor. This blower is noiseless in operation and delivers approxi- mately 200 cu. ft. of free air per minute. From the projectionist’s stand- point, an improvement of great- est convenience is provided in the unit method of assembly of the lamp. The whole lamp consists of three units : The burner assembly, the arc control assembly and the housing it- self. By merely retracting the arc control and disconnecting the pin plug on one of the main leads, the T f Va 1 i 1 ! i OCN. 71 OV0C ’0 ec 50 40 50 X, is 0 (2 O "a 0 X> IJ 10 •» pep C£MT 'OANSMiSS'ON Figure 1 between the ribbons and this density was caused to vary with the voice currents but maintained always its constant average. Under the new system of recording an auxiliary electrical circuit is asso- ciated with the light- valve, so that when the sound currents are small and the ribbons need vibrate over but a very small amplitude they are brought close together and this small vibration almost entirely tills the space between them. Then as the sound increases in loudness, so that the ribbons are required to vibrate with a greater amplitude, the spacing is automatically increased by the elec- trical circuit, so that it is always just a little more than sufficient to permit this vibration of the ribbons. This is equivalent to altering the average spacing of the ribbons, so that it is at all times proportioned to the envelope of the sound currents. Now, if we regard the amount of light which passes through the aver- age spacing of the ribbons to the film, we find that this light is considerably reduced during moments of silence or of low sounds, which results in a dark sound print. No Volume Distortiion As the ribbons open up for in- creased sound currents the amount of light correspondingly increases and a lighter sound print results. Since the actual vibration of the ribbons under Figure 2 . O. Box 'IS. General P. O., Xew York City. X. Y. Dear Sir and Brother: The “Standard Re- lease Print Makeup a n d Practice" was presented to our mem- bers. Having already handled a few of them, they were more or less familiar w i t h them and were ver\ glad to learn that the practice was to be used universally. We have no criti- cisms to offer as yet. All we can do is con- gratulate you on hav- ing induced the pro- ducers to adopt a standard system. What is now needed is a lot of co-operation between operators and exchanges. Rest assured that Local 24u will do all they can to make what seems to lie the best thing that has happened yet, a success. Fraternally (Signed) AI. B. HALL, Sec’y-Treas., Local 24(1 Local No. D4 Harrisburg, Penna., Dec. 9. 1 93a. Air. P. A. McGuire, Box US, G. P. O., New York City. Dear Alac: It has been my intention for some time to write to you relative to the "STANDARD RE- LEASE PRINT," but I have been away so Standard Release Print Report from Oakland A very interesting report on the Standard Release Print, comes from Brother Lloyd C. Litton, President of Oakland Chapter No. 12. Brother Lit* ton says in part: “ ... . The Standard Release Print, method of changeover has been in practice at the Fox=Oakland here since its inception, the only ob= jection being the conspicuousness of the black dots and their location. The Chapter has gone cn record as indors* ing the practice. Si -L'f nle e h much of late serving the I. A. in aiding ome of our Locals get agreements T have been rather occupied. I wish to compliment all those who had a hand in the promulgating of this step which is surely in the right direction, but 1 partic- ularly wish to compliment and congratulate you for your work in seeing that it was pre- sented to the men. Any new move or standard is generally criti- cized and I would feel that things were too good if there are no knocks, but as a whole 1 believe it to be a step in the right direction even if improvements come along later which would be expected. The knockers and boosters very seldom do any work, it is the go-getter, so I hope you feel elated over the job that has been done for projectionist as pertains to the Standard Re- lease Print markings. Again complimenting you and wishing you the season's greetings and my very best wishes, I remain, Sincerely your-. (Signed) Lawrence J. Katz Local No. 177 P. O. Box 30 4, Connelsville, Pennsylvania Dec. 9, 1930 Projection Advisory Council. Box 98, Gen. Post Office. New York City. Dear Sir and Brother: Your copy of "Standard Release Print Make- up and Practice” and letter of October 31st at hand. 1 wish to acknowledge receipt of same as requested. The projectionists of this local have read the copy of this booklet and find it to be of very great assistance to any projectionist who follows the suggestions and instructions con- tained therein. If all release prints were made according to the chart printed on pages four and five of this booklet and kept in that condi- tion, there would be no excuse for bad change- overs. We believe, that every projectionist would do his part in insisting upon standard release prints and giving same proper care in his possession, and by reporting any damages of the print to the exchange from which it came projection of both sound and picture would be very greatly improved in all theatres using the ‘‘Standard Release Print.” This is the greatest step ever taken toward the betterment of film conditions and improve- ment of change-overs in sound pictures. We, therefore, wish the “Standard Release Print Makeup and Practice” a very great success and offer our services and cooperation in making it such. Sincerely yours, (Signed) ARTHUR WILKE V RICHARD VAN SLYCKER Local No. 150, I. A. T. S E. Los Angeles Gentlemen : In the interest of “Better Projection”, 1 would like to state that, in past years Union Projectionists in this country made strenuous efforts to end film mutilation, and to stop the unsightly “Punch Marks", as a means of cueing for change -overs. This of necessty was slow, hard work and was reaching the point where it was practically a success. There were and always will be projectionists that will mutilate film with scratch marks and other unsightly blemishes to cue for a change-over. These are the men who, even today, are working in the smaller and sub- urban theatres of this country. Nothing will ever stop these men from butchering film, except a means of changing over that is trust- worthy and NOT incorporated in the film. You can well imagine the surprise of the very projectionists throughout the country who work the hardest to correct the conditions of film mutilation with punch-marks when they began to receive the so-called new Standard Release Print with huge unsightly black dots in the upper right hand corners, a distinct throw-back and tearing down of hard fought E tghteen for betterment in projection. A most unusual fact is the very studios who aided in the struggle for better projection and gave every assistance within their power to help the eradication of “Punch-marks” and other unsightly means of cueing are among the foremost in handing out the black dot system and expecting the projectionists to be able to use it. The theory of the Big Black Dot is remark- able to say the least, and is that of aiding the poor projectonist in the country who is ap- parently unable to change-over without a mis- cellaneous assortment of “Punch -marks,” “Back-patches,” “Scratches," Inked-in Cros- ses" and several varieties of unknown cues. I doubt very much if a projectionist in the country ever received a “Print” that had any- where as near the same footage as when it was first released and the former cue cards they sent with some pictures were worse than useless due to someone up the line doubling up the show and leaving plenty of frames out when re-assemblng. In the city the system of using the Huge Black Dots is a joke. In second and third run theatres they are unable to use them as the majority are missing anil back patches and scratch marks are substituted through necessity. In one print it was noticed that a combinat on of near y all the o'd evil i plus the hugeblack dots on some reels (that the exchange never replaces) and someone had hand painted a choice assortment of black blotches for cues. How the sponsors of the Huge Black Dots expect tin- poor country projectionist to lie able to use something in n lie out of ten cases he will never get is what is puzzling a good many old heads in the business. The Huge Black Dots” are annoying to the audiences who wonder why the projectionists put big black blotches on the film and when it's a dark scene put a halo around the lilotch. If this isn't a reversion to the old days when cranking a machine was the height of some- thing or other, what is? How any group of men could he insane enough to try to foster anything like this on the modern projectionist is hard to realize. There is only one answer and that is an attempt at personal publicity by the parties responsib.e for the black dot system. It is to the discredit of the Projection Ad- visory Council that they would permit their names to he used in sponsoring a proven worth- less and unsightly means of changing from one machine to another. It is apparent that they did not properly investigate the merits of the proposed ‘Standard Release Prints" which shows nothing in this long heralded and highly publicized release print that is supposed to aid the projectionist, that has not been in use off and on for many years. It certainly seems that this is another at- tempt to indulge in the popular past-time of passing the buck to the projectionist. Yours very truly, (Signed) Richard Van Slyker, Local No. 150, 1. A. T. S. E. January 5th 1931. Bridgeport, Connecticut. 452 Windsor Avenue, Stratford Connecticut, December 21. 1930. Projection Advisory Council. Box 98, General Post Office, New York, N. Y. Dear Gentlemen: We have considered the problem of Standard film change-overs at a special meeting of Local 277 of Bridgeport, Connecticut. The criticism of each member is identical. It is as follows: They find the footage marking at the be- ginning of reel to be very helpful. They are perfectly satisfied with this. However, when one prepared to change-over from one machine to another you might accidentally blink your eyes. For example if you are preparing to change from No. 1 reel to No. 2 reel, you are staring through the port -hole awaiting the markings on the film. If. however, you blink (Continued on Page 33) TRANSFORMERS AS APPLIED TO PUSH-PULL CIRCUITS The 246-A input transformer in the 49-A amplifier is somewhat simi- lar to the Clough type. Plate cur- rent is supplied to the tube through a 375000 ohm resistance. One end of the primary is connected to the tube by an isolating condenser and the other end returns directly to the filament of the tube. In the Clough transformer the return from the pri- mary is through the C bias, which is necessary because the primary and the secondary are one winding. This is one of the differences between the two transformers. The primary and secondary on the 246-A transformer are entirely separate. There are points for and against both methods. Where the return from the primary is made directly to the filament all filtering problems are done away with. When the primary and the secondary are the same winding the return must be made to minus C, which causes the signal currents in the primary to flow through the C bias resistance. If this is not well bypassed by a large condenser it is apt to cause feed-back, which may be positive or negative, and may or may not be serious, depending on the design of the amplifier. In the case where both the primary and the secondary are common it usually requires less wire for the same voltage step-up than it does where the two are separate windings. In the 246-A this is offset by using permalloy for the core. Permalloy is a core material having extremely high permeability. This means that for any specified degree of magnetization it requires less turns on the primary for the permalloy core than it does for the core made of ordinary material. When it is pos- sible to use fewer turns in the pri- mary the step-up ratio can be made greater. This is because the num- ber of secondary turns are limited, as was mentioned in the early part of this series, for the reason that the high frequencies are bypassed more and more as the number of secondary turns are increased. Now you say, why not reduce the primary of the transformer using the ordinary core? This would give the higher ratio of transformation all right, and above three hundred cycles this plan would work very well, but on the lower frequencies the signal would not be transferred from the tube to the transformer efficiently. This is because the inductance falls off at the low frequencies, and when the inductance drops the impedance also drops. To efficiently transfer the signal from the tube to the trans- former the primary impedance at the V / u e te e n lowest frequency to be amplified must be at least twice the plate impedance of the tube. This means that the primary cannot be reduced and still have good reproduction of the low notes unless a core is used that has a higher permeability. The drawback in the use of perm- alloy is that it saturates so easily, and when once saturated, or if it re- ceives a sharp blow, its magnetic properties are ruined. It can no longer be used. That is why no plate current is allowed to flow through the windings. This must also be kept in mind when testing. To test one of these transformers in the ordinary way would ruin it. This will be taken up at greater length in the chapter on testing. Getting back to the more conven- tional types of transformers again, let us see what is required to prevent saturation. The shunt feed method can be used in connection with any transformer, and in the writer’s opinion will improve the performance whenever used, with one exception. This is when a transformer is de- signed for a large plate current, but is used with a tube that draws only a small plate current. The term shunt feed is applied to the type of circuits we have been discussing, where the plate is fed through a resistance and A STAGE OF PUSH-PULL the signal goes to the transformer through a condenser. In the design of modern transform- ers the manufacturer takes steps to keep the core from becoming saturat- T avert ty ed, and this is done by making the core large enough so that the primary current does not cause saturation. Someone suggested a method to counteract saturation by putting an additional winding on the trans- former. This winding is similar to the primary, and a current having the same value as the steady plate current is passed through it in such a direction that it tends to produce a flux in the core in the opposite di- rection that the plate current pro- duces. The sum of the two effects is zero. No flux is produced in the core excepting that due to the signal. As far as the elimination of the tendency of the core to saturate, the idea is O. K., but there are other things wrong with it, among which is the fact that the additional winding acts as another secondary, a partially shorted secondary, which puts a load on the primary. This is not desirable as a rule. So far no one has put out such a transformer. In push-pull output transformers saturation effects are not present to any great extent. The primary is tapped in the exact center. This point is connected to positive B. The ends of the primary connected to the plates of the output tubes. When the tubes are evenly balanced, when they draw the same plate current, the current from one tube tends to produce a flux in one direction and the current frcm the other tube tends to produce a flux in the opposite direction. The total flux due to the steady plate current is zero. When the tubes are not ex- actly alike a flux is set up in the core by the difference of the two currents. If one tube takes 30 mils and the other takes 31 mils a magnetic flux is produced in the core of the same strength as would be produced by a current of 1 mil flowing through one- half of the primary winding, which is not serious. This is one of the reasons why the tubes in any push- pull stage should be as nearly alike as possible. One maker puts out a push-pull input transformer of the Clough type. TWO STAGES OF PUSH-PULL In push-pull input transformers the ends of the secondary go to the grids of the tubes in the push-pull stage. Being of the Clough type the primary is part of the secondary, and the center tap must go to negative C. The other end of the primary is an- other tap taken off of one of the halves of the secondary. This tap is connected to the isolating condenser, just as it was in the single side Clough transformer. The plate is fed through a coupling resistance. This transformer combines the features of push-pull and of the Clough system. At first thought one may think why use the Clough system when push- pull balances out any magnetization due to the plate current. That is true cf the transformer described in the above paragraph, but that one was an output transformer, the plates of two tubes were feeding into the trans- former. This one is an input trans- former. There is only one tube feed- ing into the primary. There are not two plate currents that can counter- act each other. The one steady plate current will tend to magnetize the core if it is allowed to flow through the winding. The Clough system pre- vents this. The use of push-pull makes it easier to obtain good quality and hum free reproduction. Any hum intro- duced into the system by heating the filaments with AC balances out, un- less the grid and plate returns are way off center. Any small ripple left in the plate supply after filtering also balances out. A push-pull stage can be constructed so that rectified but unfiltered current can be supplied to the plates of the tubes and still get hum-free reproduction. This is part- ly due to the fact that it is the last stage. There is no amplification be- yond this point. Such a thing is im- possible in the preceding stages. While a stage of push-pull is itself more costly than straight single side amplification is, the extra cost can nearly be offset by a smaller filter in the plate supply. Another item is the saving in the plate and grid cir- cuit filters, which usually are neces- sary to prevent feed-back. In the power stage of an amplifier the signal currents are large and when push-pull is not used the filter- ing of these currents is often a prob- lem, as they must be kept out of the plate supply, neither can they be al- lowed to flow through the grid bias resistance, as either of these will cause feed-back, to the grid of the power stage, or, what is still worse, to some of the circuits in the preced- ing stages. In a stage of push-pull this is not a problem since the total current taken by the tubes is nearly constant. When one of the tubes is taking maxi- mum plate current the other is taking a minimum current. As the current drawn by the first tube starts to de- crease the current taken by the sec- ond tube starts to increase. Besides input and output push-pull transformers there are also inter- stage push-pull transformers. When these are used the last stage and the stage preceding it are both push-pull. In these transformers both the pri- mary and the secondary are center tapped. The tap on the primary go- ing to positives B and the tap on the secondary going to negative C. Two such stages give extremely high qual- ity of reproduction. i i i CHAPTER SEVEN DUES DUE Bro. H. R. Cage, Treasurer of Cali- fornia Chapter No. 7, announces that the first quarter dues are now pay- able. Checks should be made pay- able to American Projection Society Chapter No. 7. This applies only to the members of this Chapter. T wenty -one HOW TO STUDY Continued from page 8 in real effort necessary to excell in anything, or the man who all his life has merely played at swimming? Is it not probably true also that the man who merely played did not get as much real enjoyment out of his play- ing as the other did when working hardest to accomplish what he set out to do. The same thing holds true of studying anything. The one who earnestly and honestly tries, never willing to admit that what others can do he cannot do, is the one who is headed for success. He is also the one who gets the most enduring en- joyment out of life. In beginning to study, remember one more thing, namely, the hardest effort comes at first. Once one really forms the habit of studying, it ceases to be an effort. The more one learns, the easier studying becomes. Things which seemed difficult have a way of becoming easy when tackled with courage, and the satisfaction of ac- complishment far outweighs the ef- fort expended. HOW TO READ Practically any line of studying in- volves reading, since practically all of the knowledge won by the human race sooner or later finds its way into books. Books are a record of the ac- cumulated experience of mankind, and if we are to profit by the things which others have found out, we must get a large part of our knowledge from the printed page. Few people read effectively. They read the words, but the ideas remain vague. When they have finished reading a book, unless it happens to be a story, they would find it difficult to remem- ber accurately and clearly a half dozen things included in the book, and those things would more likely be dis- connected illustrations than the fun- damental truths which the illustra- tions were meant to clarify. To get out of this bad habit, try repeating to yourself at the end of each paragraph the gist of the subject matter con- tained in it. With oractice this should become easy. With a little more practice, one can readily recall the essential ideas of a whole chapter. To do this, something more than mere memory is necessary. The sub- ject matter must be understood. One must think as he reads, see why things are so, note the various steps through which the author arrives at a conclusion, weigh the evidence, try to draw conclusions independent of those drawn in the book. Do not accept blindly anything merely be- cause it is printed in a book. Ask yourself whether a statement sounds reasonable. If it does not sound rea- sonable, is it because it is clearly con- trary to common sense or may it not sound unreasonable merely because you know so little about the subject. In the latter case, consider the relia- bility of the author. Is he in the hab- it of making wild statements, does he tend to exaggerate, have you found him to be inaccurate or careless, or purposely misleading? This habit of weighing the evidence, of basing con- clusions on facts rather than on prej- udice, is one of the most valuable ad- vantages to be gained from careful systematic study. When reading, have a dictionary close at hand and use it. Make sure that you know the meaning of every word you read. This is especially im- portant when reading scientific ar- ticles, where accurate knowledge of the meaning of terms is necessary to a correct knowledge of the subject. Moreover, keep a record of the things read, so that if you ever wish to apply the knowledge you may quickly and easily find the article in question to refresh or to make sure of the ac- curacy of your memory. Also make a list of things not understood, so that you can look them up in further detail in some other book or ask some- one who knows to explain them to you. T e >1 fy -t-xv o HOW TO LISTEN TO A LECTURE One of the most important aids in getting the most good from any lec- ture is to think about the subject be- forehand. Determine what you al- ready know, and things about which you particularly wish to find out. Pick out the doubtful points which you hope the lecture may clear up. Then listen to the lecture attentively, thinking as you listen. Take notes, but not too copiously. Do not try to get everything down on paper. Pick out the important principles, the fundamental ideas. Watch for key words, which will recall the subject matter to you vividly when you re- view the lecture. If anything is not clear or if you do not agree with the soea^or. do not try to settle the ques- tion in your own mind then. If you think too long on a doubtful point, you will miss the following points in the lecture, possibly losing the thread of it entirely. Merely jot down a word or two to enable you to remember to think the doubtful matter out in de- tail later. If, after the lecture, there is op- portunity to ask questions, do not hes- itate to seek to clear up in your own mind doubtful points. The man who is not ashamed to ask questions is the man who learns. Never pretend to know what you do not know. Do not say you understand when you do not. Only a fool is afraid of betraying his ignorance by asking a question. Think over the lecture afterward. Try to make an outline of it, first the main points, then fill in the details and illustrations or examples. Seek to tie up the new knowledge with things already known. Ask yourself why things are so, how they have probably been ascertained, whether a knowledge of them is important, how you can use the knowledge. TEST YOUR UNDERSTANDING One of the finest ways of testing your understanding of a subject is to write what you know about it, for clear and logical writing requires clear and logical thinking. Make an outline first. Think the subject over carefully, form clear ideas. Decide where to go to get further material on the subject or to clear up doubtful matters. Finally, put your books to one side and write your ideas in the best English you are capable of using. Include sketches if they will make the subject any clearer. Then read care- fully what you have written. See if you can make it any clearer, easier to understand, or more convincing. Think up all conceivable arguments against what you have written, and see if you can prove that these argu- ments are erroneous. Another test of your understand- ing of a subject is to work problems illustrating the principles involved. When problems are assigned, try working them in several different ways. Try to devise some way to test the accuracy of your answers. Above all, see that every answer is a reason- able one. It is often possible to guess fairly closely what an answer will probably be. Try guessing the an- swer before the problem is worked. This often is the means of catching a numerical error in your work which leads to a ridiculous answer. Make up similar problems and work them so as to get added experience. Do not say that you cannot work a problem because you do not under- stand mathematics. This usually means that you are unwilling to make the effort to think. First formulate the problem clearly. Be sure that you know definitely what is to be de- termined. Then put down what data is known, also what things apparently must be used to get the final result. See whether you can obtain these nec- essary data from the data at hand. Determine the logical steps of reason- ing to obtain the desired answer. When problems are returned, marked wrong, always remark them. Prove to yourself that you can get the correct answer. The way to clarify your own ideas is to concentrate on correcting your mistakes. The third method of testing your own understanding of a subject is to (Concluded on Page 25) T M ♦.« ♦.« ♦.< ♦ < MAINTAINING QUALITY IS TRUE ECONOMY TAe/nternat/ona/ fEo/ector l The International Projector | ♦> THREE PROJECTORS I % % OR I EMERGENCY EQUIPMENT KEPT IN A1 CONDITION Z IS A SURE INDICATION I OF ! PRACTICAL-PROGRESSIVE SHOWMANSHIP i i ❖ BETTER PROJECTION PAYS ❖ International Projection Corporation 90 Gold Street, New York * X One ■-3 0 Ig . . y y ^r-g EDDIE HARRIS [ Asks — ; "Are YOU Interested In A WELDED Film Splice — or — Does JUST A PATCH ■ Satisfy You?" Our Slogan: "The Splice is Stronger Than the Film Itself," is not merely a "catch-word" — It means that the break in the ; film is ACTUALLY welded as steel is welded — FOR PERMANENCY! We feel, at this time, that an analysis of the working of ODORLESS— FLAMEPROOF— 2 in 1* FILM CEMENT and the ordinary QUICK DRYING cements on the market, will clear up ! ! a mis-understanding as to the value of a quick drying cement and j| ; one of less volatility. ! To WELD a break you must FUSE and MELT the broken pieces I into each other to become ONE. To PATCH a break you just use an adhesive to make TWO SPTRFACES stick to each other \ ' FOR THE TIME BEING — They will come apart — in the case of ' film, ether will do that. 1 ! Ether being highly volatile, dries quick, hence can only get a [ surface grip on the film and soon opens ! : ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT having • low volatility evaporates slower BUT melts and fuses the broken film into a WHOLE. ! 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Some valuable terri- tory still open. We also manufacture com- plete sound on films and disc equipment for sound pictures. Write us today. This unit will stand an input of 25 watts con- tinuously. The voice cod is wound directly on dia- phragm thereby elimi- nating coil mountings which have been the chief cause of trouble in other units. Voice coil is self cooling and will not burn out. Unit fully covered by pat- ents issued and pend- ing. FOX ELECTRIC & MFC. CO. 3120 Monroe Street Toledo, Ohio B- Earning the confidence of an industry... Watch this space for • announcement of • New Magnascope Unit Weaver Bros. Manufacturing Co. LOS ANGELES, CALIFORNIA Manufacturers of Weaver Auto Douser Weaver Curtain Control Distributed by Distributed by All Theatrical Supply Houses Scenic Studios o u r A Technical and Educational Publication. Devoted to the Western Projectionist and his Progressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G CROWLEY H. E. ALFORD Supervising Editor Edifor-in-chief Business Manager W. R. HERMACNE l26^ Wellon Way A. L. FEINSTEIN Staff Photographer Inglewood Calif. Pleasant7332 Circulation JAMES B. GILLARD, Oakland Editor Technical Editors, 1436 Delaware St. Berkely, Calif. A. C. SCHROEDER, D. B. McGOWN Volume II. MARCH, 1931 Number 3 CONTENTS The Modern Portable By Chas. Watson 7 Characteristics of High Intensity Arcs By D. B. Joy and A. C. Downes 9 Nature of Light By Robert D. Clark, A. P. S. . . . 13 Showmanship By Lloyd C. Litton, A. P. S 16 Standard Release Print Progressing 17 Academy Officials Discuss Standard With Projectionists 19 Give the Musicians a Break By J. B. G 20 Craft Technical Data By A. C. Schroeder .... 21 Just How Clever Are You? 24 First Oakland Meeting for 1931 By Geo. J. Lancaster, A. P. S 25 Things in General By the Editor 28 Pin Spots 29 Chapter Doings — California Chapter No. 7 and San Bernardino Chapter No. 19 30 Secretarial Comment — California Chapter No. 7 31 Condenser System for Wide Film By E. H. Rooney 35 Health Talks for Projectionists 36 Published Monthly, Sponsored by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. In Groups of Five or More, $1.00. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Blvd., Los Angeles, California JHve The A. P. S. Cleveland Chapter Says: "The Best Book on the Subject Available" SOUND PICTURES MOTION PICTURE PROJECTION By JAMES R. CAMERON Introduced by S. L. Rothafel (Roxy) 1280 Pages — 500 Illustrations Fourth Edition The Largest, Latest and Most Compre- hensive Book on the Subject Published PRICE— SIX DOLLARS By JAMES R. CAMERON Introduction Bu WILLIAM F. CANAVAN Pres. I. A. T. S. E., M. P. M. O. OVER 1,100 PAGES 500 Illustrations The whole question of Sound Motion Pictures treated from a new angle. A Capable Guide For Trouble Shooting Explains in detail the con- struction, operation and care of sound recording and re- producing equipment. We care not how many books you have on the subject — here’s one that’s DIFFERENT One that you’ll find a daily use for — one ENCYCLOPEDIA On Sound Motion Pictures Here is a book containing over 2000 subjects allied with the Making and Showing of Sound Pictures. A book that makes both instructive and interest- ing reading. PRICE THREE=FIFTY ARTHUR GRAY, Lancaster Theater, Boston, Mass.: “All of your books are of a consistent high standard and SOUND PICTURES AND TROUBLE SHOOT- ERS MANUAL and the EN- CYCLOPEDIA are smashing hits if I am any judge of what projectionists want — A veritable mine of valuable information.” HARRY RUBIN (Chief of Projection, Publix Theatres): The most complete book on the subject published — should be in every projection room in the country. AMERICAN PROJECTION. 1ST: “The best book on the subject now available, or likely to be available for a long time to come.” R. C. A. PHOTOPHONE: “ — a splendid comprehen- sive addition to the litera- ture of a new entertainment SOCIETY OF MOTION PIC- TUR ENGINEERS, PRO- GRESS COMMITTEE: “A notable publication — Motion Picture Projection by Cameron is extremely com- plete covering all phases of motion picture engineering.” WE’LL BE PLEASED TO SEND YOU A COMPLETE LIST OF OUR PUBLICATIONS You Cannot Afford To Be Without EVERY KNOWN TROUBLE TO SOUND RE= CORDING AND REPRODUCING EQUIPMENT IS LISTED IN THIS BOOK— WITH FULL EXPLANATION AS TO ITS CAUSE AND REMEDY Price — Seven-Fifty CAMERON’S CAMERON PUBLISHING COMPANY, INC. Manhattan Beach, New York Six The Mod ern Portable by CHAS. WATSON, Radio Engineer The portable sound system herein described is the result of consider- able time and engineering skill in producing an equipment that would have as many desirable features as possible and at the same time pre- serving the compactness necessary in a portable apparatus. The outstanding feature of the Zenith Portable is its use of the standard Zenith projector mechanism with a sound head built in conjunc- tion with it. The fact that most pro- jectionists are already familiar with this head is an added advantage. No expense has been spared in the construction of the electrical system to make it efficient, powerful and as portable as possible without sacrific- ing any points that are necessary to obtain good reproduction. In describing the electrical system we will not delve into technicalities but will explain the operation and general characteristics of the ampli- fiers, etc., with the object in mind of *Designer of the Zenith Portable Sound System. Seven giving to the projectionists a general working knowledge of the system. High Gain Obtained We attribute the general compact- ness and exceedingly high gain of the amplifiers to the correct use and very high gain of the uy224 and ux224 tubes. As you will note in the accompany- ing diagram the input stage of the amplifier uses a ux224 tube and the preceding stage uses a ux230 the filaments of which are connected in series with a dry cell battery supply. The filament current is very low (60 milliamperes) and can be regulated by the variable resistance R3. In order to compensate for the irregularities in the characteristics of the ux224 tubes a variable screen voltage regulator is used and when replacement tubes are necessary the plate current can be readily adjusted by its use in connection with the plate milliameter and push button marked ux224. The milliameter in the circuit serves a triple purpose, namely plate mills of the ux224, which is .3 of a mill, plate mills of the ux230, which is 2.5 mills, and also the filament cur- rent which is as we mentioned before 60 milliamperes. These tubes are tested by means of the push buttons. It is also worthy of note that the fila- ments of both can be watched closely, thereby prolonging their life. Correct impedance relationship is very necessary in this method of using the screen grid tube involving high input plate voltage and resist- ance coupling from the plate of the 24 to the grid of the 230. As will be noted from the diagram the input plate voltage to the 24 is 450 volts, the plate resistor being 750,000 ohms, thus introducing high impedance and a high voltage drop. Using a higher resistance value than 750,000 has a tendency toward non-clarity and should not be used. Shielding Effective Through Isolation Due to the fact that even with the best of shielding and the most care- fully laid out wiring system used (Continued on Page 27) E i g h t Schematic of PFC ond Vo/tac/2. Amp/if/ers Zzn'.th Por+ab'e. S o i/ncJ Sysf CORPS NT Figure Two from the high intensity arc as mea- sured directly in front of the crater. The additional light comes almost entirely from the tail flame which streams out of the positive crater. The candle power as well as the steadiness of operation is affected by the angle and relative position of the negative carbon with respect to the positive crater and by the voltage maintained across the arc. The angle is usually fixed by the construction of the lamp. The best results were obtained when the relative positions of the negative carbon and positive crater were such that the negative flame just brushed the lower edge of the positive crater as shown in Fig. 3 -A. If the negative flame bathed the Discussion of Results The candle power of the crater light directly in front of the arc is shown in Fig. 2. As would be ex- pected the candle power increases with the current. When the same current is used on two different size carbons of the same composition, the smaller size carbon, that is, the one Ten lower outside of the positive crater appreciably, as shown in Fig. 3 -B, the candle power decreased probably because some of the current was taken on the outside of the positive crater thus lowering the current and energy concentration on the inside of the crater. If the edge of the nega- tive flame were considerably ahead of the lower edge of the positive crater as shown in Fig. 3 -C, it would not have as much tendency to keep the hot gases in the crater and would re- sult in a lower candle power. It was found in the case of the 16 mm. car- bons in the current range of 140-150 amperes, which is ordinarily used, that the best arc voltage was 73-83 volts. Below this voltage the nega- tive was so close to the positive that the negative flame appeared to im- pinge on the hot gases in the positive crater with such force as to actually drive them out with a consequent unsteadiness and loss of light. Above this voltage the negative was so far away from the positive that the nega- tive flame apparently lacked the nec- essary force to confine the gases in the positive crater and caused a loss of light from the crater area. With lower currents, lower voltages can be used. The 13.6 mm. carbons in the cur- rent range of 110-125 amperes oper- ated best at approximately 67-73 volts and the 8 mm. carbons in the current range of 60-70 amperes op- erated best at 48-55 volts. In general, if lower currents are used, the volt- Nationai High Intensity Carbons HORIZONTAL ANGLE FROM AXIS OF POSITIVE CARBON Figure Four age should be correspondingly de- creased. The effect of lower and higher voltages with the 9 mm. and 13.6 mm. carbons is the same as with the 16 mm. carbons although to a somewhat smaller degree. The angular distributions of candle power from the positive craters of 9, 13.6, and 16 mm. carbons in the horizontal plane in a total angle of 80 degrees are given in Fig. 4 for a number of different currents. The candle power is slightly lower directly in front of the crater than at 10 to 20 degrees on either side. The candle power holds up remarkably well to the 40-degree limit measured and is only 10 to 17 per cent lower at 40 degrees than at the center. This ac- counts for the decided increase in the useful light from the high intensity arc when a mirror or condensers of large effective angle10 are substituted for the old style condensing lenses of small effective angle. The light distribution is approxi- mately the same for the different sizes of carbons and the different current values investigated as is clearly shown in Fig. 4. The areas of the crater openings of the different size carbons at the various currents are given in Fig. 5. — r — i — i — i — i — National High Intensity Carbons CRATEJ 7 OPENING VS. 1 ^6M A UKkLN 1 1.6 MM. 9MM. 50 60 TO 60 90 100 1IO 120 130 VOO ISO 160 CURRENT Figure Five The cross-sectional areas of the 9 mm., 13.6 mm., and 16 mm. high in- tensity carbons are 64 sq. mm., 145 sq. mm., and 201 sq. mm., respect- ively. It is obvious from the curves that the crater openings for even the higher currents are much less than the original carbon cross-section. Eleven The decrease in crater opening for the lower current densities is due in part to the increased spindle or taper- ing of the portion of the carbon pro- jecting from the positive holder. This increased tapering is due to the enor- mous decrease in the length of carbon consumed per unit of time for a small decrease in current which allows a longer time for the hot surface of the carbon close to the crater to burn away. The size of the crater opening or light source of the high intensity car- bons is important in considering the application of any optical system for it has long been recognized and clearly demonstrated before this So- ciety11-12 that the light efficiency for motion picture projection decreases rapidly as the area of the light source increases. The intrinsic brilliancies in candle power per square millimeter of crater opening have been calculated from the above values of candle power and crater opening and are plotted in Fig. 6. As in the case of the candle power, the intrinsic brilliancy increases very rapidly as the current is increased on any given size carbon. The values come within the range of those given in the literature1-7. It is believed, however, that this is the first time that data showing the change in in- trinsic brilliancy for the currents and sizes of high intensity carbons have been compiled. It is interesting to note that practically the same intrin- sic brilliancies are obtained with the various sizes of carbons at the cur- rents ordinarily used. These values, ranging from 500 to 750 candle power per square millimeter, illustrate quite forcibly the advantage that the high intensity arc has for projection pur- poses over the plain carbon arc with an intrinsic brilliancy of 130 candle power per square millimeter and the incandescent tungsten filament pro- jector lamp run at overvoltage with an intrinsic brilliancy of 27 candle power per square millimeter.13 Typical curves of the spectral en- ergy distribution of the light from the craters of high intensity arcs are given in Fig. 7. The distribution AN6STPOM Units Figure Seven closely approximates that of sun- light.9 The curves show that there is approximately the same amount of energy in the blue region as in the red region for the lower currents on the carbons. As these currents are increased as evidenced by the curves for the 13.6 mm. carbons, the red end of the curve increases faster than the blue so that at the high currents there is actually an appreciable prepon- derance of red as compared with blue. This is contrary to the distribution curves given in the Bureau of Stand- ards Scientific Paper No. 539, but, as stated previously, the measure- ments tabulated in that paper were made on the unscreened arc and in- cluded the light from the negative arc stream and tail flame which amounts to approximately 32 per cent of the total light and which is known to give (Continued on Page 26) Tnve l5 If we consider the whole wave in- stead of having only two points such that WC equals PC plus half the wave length of the light, there are an in- finite number of points in a circle around P that satisfy this condition. In the same way there ai*e circles through XX, YY, etc. These circles divide the plane wave into a circle and concentric rings that are known as half period elements. The waves from each of these elements interfere with waves from adjacent elements. To get the effective illumination at C we must sum up the effect of all the elements. There is a change in area of elements as one goes outward from P. There is also a change in intensity of illumination with increasing obli- quity of the rays. The result of these two is that practically all of the ef- fective illumination comes from com- paratively few zones surrounding the pole. For elements farther out there is almost complete cancellation. By mathematical and practical de- monstration it has been found that the illumination at C is equal to one- half the illumination from the first element plus one-half the illumination from the last element. In cases where the last element is far away the second term is negligible. How- ever, if we have P at quite a distance from C, and use a camera aiaphrac m to cut out the more distant elements, the effect of this second term is marked. Suppose we stop down until we have an even number of half period elements. Then the first and last elements will be out of phase when they reach C and there will be little light. If we have an uneven number of elements, the first and last will be in phase. They will reinforce and there will be more light at C than if there were no diaphragm there. Because of this rather strange action of interference it is true that we would get more light at C from the first element alone than from the whole wave. How does this apply to the recti- linear propagation of light? Recti- linear propagation is only an ap- proximation due to the short wave length of light. As in Figure 1 the waves do go around the corner, but they interfere and produce darkness. At point Q, Figure 1, there will be illumination, but not the full illu- mination of the wave, for half the first elements of the wave have been cut off. Below Q the light will grow gradually dimmer as more and more of the effective elements are cut off by YP. Finally, say at J, all the ef- fective or only partly interfering Fourteen waves will have been cut off and we have complete darkness below J. This anpdes to waves other than plane with a similar proof. To show why we can generally ne- glect bending, the diameter of the first zone for orange light and at 50 cm. from the light source is 0.05 cm. For a sound wave of middle C on the piano the corresponding diameter is about 76 cm. Studying the shadow cast by an illuminated sharp edge we find that the light encroaches on the geometri- cal shadow, and the shadow on the light, but not with uniform diminu- tion on both sides. Instead, there are light and dark bands in the light. These bands are called diffraction fringes. Figure 4- Let C be a luminous point emitting spherical waves, AZB a section of a wave, ZD an opaque obstacle with a straight edge perpendicular to the plane of the paper, RV a screen. Now to find the illumination on RV. Let us consider the point R. W is the pole of R. We can consider the illumination at R the sum of the full half of the wave above W plus that part of the wave below W that is is not obscured by the screen. We can divide the wave into half period elements as with the plane wave. Suppose WZ contains all the effective center zones of the wave. Then from R up we have uniform illumination. Below R there is a point S such that from X, its pole, to Z there is an even number of half period elements. There will be interference of the waves coming from X and Z and we will have a spot of minimum illumi- nation. Between the pole of T and Z there are an odd number of half period elements and we have waves from Y and Z in phase to make a bright spot at T. Between R and U there are a succession of these maxi- ma and minima that we call diffrac- tion fringes. Below U the illumination will grow gradually dimmer as explained before. The main part of the illu- mination below U comes from the first zone that is not cut off. As these diminish gradually the diminution of effect from U to V has no maxima or minima. If instead of ZD we have a narrow strip AB, we get fringes in the geo- metrical shadow as well as in the illu- minated portion. The strip must be narrow enough that the light that is bent into the shadow from A and that bent in from B will overlap and pro- duce fringes, as at XY. These are two types of diffraction (Continued on Page 33) F i fte e n SHOWMANSHIP by LLOYD C. LITTON, A. P. S. In our mad scramble to adjust our- selves to the addition of Sound to our projection equipment we have been so busy studying Sound Amplification, Reproduction and all the technical things that go with it that we have overlooked what I consider the great- est asset any projectionist can be endowed with, showmanship! To even attempt to define the word “showmanship” is a bigger job than I care to tackle, because, it covers a multitude of qualities in various lines of theatrical endeavor. I do believe however, that I know what qualities it covers in a projectionist. To begin with, a high grade Pro- jectionist must possess several quali- fications, he must have a thorough knowledge of mechanics to be able to recognize the effects of wear and mal- adjustment by analyzing the pro- jected picture, he must be quite a skilled mechanic also to be able to service and maintain a moving pic- ture projector properly, he must understand optic projection and have a good working knowledge of lenses and their application to moving pic- ture projection, his knowledge of electricity, since the coming of sound amplification systems, should border on Engineering, to say nothing of what he should know about Theatre acoustics, etc., etc., yet possessing all these qualities does not mean that his work as a Projectionist will be the best, it is only when he combines all these qualities with a sense of Show- manship, that he becomes the real Projectionist. I would say that a Projectionist is developing a sense of showmanship when he begins to realize that the results of all his skill and knowledge go for one thing only, the entertain- ment of others. LLOYD C. LITTON. President Oakland Chapter No. 12, A. P. S. It is then that he begins to work from an Audience point of view, he develops smoothness and ease of operation in handling the equipment, curtains close, lights come up, effects go on, change overs are made with clocklike precision, emergencies are covered with calm judgment instead of distraction, in short, the show goes on with smooth continuity and noth- ing happens to detract from the en- tertainment value of the perform- ance. His work becomes a pleasure in- stead of a nerve wracking job, he discovers there is technique in the handling of spots, floods and effects on prologues, overtures and stage reviews, his own personality creeps into his work and is reflected if the audience applauds an act or an over- ture they are not only applauding the particular performer or leader, but they are also applauding everything that went into making their per- formance a success, gives him a thrill of pleasure at their appreciation of his own contribution. His jealousy of another’s ability and success gives way to admiration and he secretly applauds a well ex- ecuted piece of work, in short, he be- comes a real CRAFTSMAN instead of just a tradesman. Sixteen Standard Release Print Progressing When the technical bureau of The Academy of Motion Picture Arts and Sciences asked for inquiries and sug- gestions from the projectionists con- cerning the Standard Release Print make up which has been adopted by the producers, they probably did not anticipate the deluge of criticism and praise which has been rained upon them from projectionists all over the country. The system was developed under the direct supervision of Les- ter Cowan, manager of the academy technical bureau, who appointed S. J, Twining chairman of the Stand- ard Release Print committee. During the development of the standard this committee worked very closely with the Projection Advisory Council and the American Projection Society. Mr. Twining recognized this help by the projectionists organization by saying in part: “Acknowledgement is hereby ex- pressed on behalf of the Academy to the many technicians who contribut- ed to the development of the Standard — including representatives of the seventeen major Hollywood studios, the Association of Motion Picture Producers, and the Hollywood chap- ters of the American Projection So- ciety, the American Society of Cine- matographers, and the Society of Motion Picture Engineers — to the Motion Picture Producers and Dis- tributors of America for assistance in putting the Standard into effect, and to the Film Boards of Trade, the Projection Advisory Council and the American Projection Society for help in the maintenance and further de- velopment of the Standard.” He further demonstrated his broad- mindedness and co-operative spirit by saying : “The specifications will be revised from time to time as necessary to further the general purpose of con- tributing to the highest quality of sound picture presentation.” This statement expressed more than anything else that the Academy expected that revisals and changes would be necessary before the ideal could be attained. It is very seldom that any big change is brought about in a single step. Mr. Thad. C. Bar- rows, president of the Projection Ad- visory Council, must have realized the fact that the first Standard was not perfect when he wrote, “We be- lieve, from the projectionists’ stand- point that the Standard unquestion- ably represents a step in the right direction.” Mr. Barrows must have anticipated the present difference of opinion. No Solutions Offered A significant fact concerning the many communications which have been received by the Academy and P. A. C. from projectionists is that none offer any suggestions for a prac- tical solution of the problem. They are fairly evenly divided between praise and condemnation which seems to point rather sharply to that fact that some changes, small ones, perhaps, but changes nevertheless, may be necessary. A. P. S. to Offer Recommendation Realizing the possibility of im- provement to the Standard as it is now and realizing that its originators recognized the fact that from time to time revisals and improvements would present themselves which could be advantageously incorporated, Sid- ney Burton, president of California Chapter No. 7 of the American Pro- jection Society, has set in motion a plan to secure a practical and work- able improvement for the Standard. President Burton appointed a com- mittee from the membership of Chap- ter No. 7 consisting of Wallace J. Maxon, Frank Erler, Ed Keller, James Pointer and T. H. Eckerson. The work of this committee will be to formulate a suggestion for improving the Standard. This suggestion will Seventeen be submitted to the Academy commit- tee for approval and adoption or re- jection. Other Chapters Invited President Burton has, in collabora- tion with this publication, invited all the presidents of the various A. P. S. chapters to appoint committees to consider the many phases of the Standard and make whatever recom- mendations they deem advisable for its improvement. It is expected that the different chapters will be very anxious to co-operate with the Aca- demy and the P. A. C. in this way. The aggregation of plans coming from the several committees will no doubt present angles which will prove invaluable. Messrs. Lester Cowan, S. J. Twining, Thad. C. Barrows, P. A. McGuire, Sidney Burton and many others are working very hard to per- fect and put into practice a Standard which will prevent, by rendering it unnecessary, all unsightly scratches, etc., which have formerly been used for changeover cues. Individuals Invited to Write If you are not appointed on a com- mittee or if you are not a member of the A. P. S. you are cordially invited to send to this publication your com- ments and suggestions. Only by this method can the industry be given the benefit of your idea. You owe it to yourself with those others who are giving of their time and knowledge for the benefit of the industry. Write in your suggestions today. i i i It is our policy to print each month those letters that come to us from the projectionists in the field. Their re- actions and comments are most valu- able to the Academy. The following letters display con- siderable thought on the part of the authors and merit your considera- tion : Oakland, Calif., Jan. 19, 1931. Mr. Sidney Burton, Projection Advisory Council, S126 Norton Ave., Hollywood, Calif. Dear Mr. Burton: Regarding the Standard Release Print, have an appointment Monday, 2:00 p. m., with the S. F. Film Board of Trade. Will send you a detailed report of the proceedings. Do you think it would be practical for the E i g h t e e n producers to ship or assemble their features in two thousand-foot reels instead of the thou- sand? Since many of the brush houses and others have reverted back to the one man some taking out the turntables, I firmly believe that the doubled reels would solve much of the trouble we are trying to cope. Routine of a brush house operator runs like this: Reports to work at 6:30 p. m. New show coming in. Starts the amplifier set, dashes for the News and Comedy. Rewinds to mark for curtain S. M. and C. O. and how. Then cuts in a trailer and then doubles on the feature. He probably by now has one and two of the features hooked up. Warms up th ■ projectors, trims the lamps, threads up and starts the show at seven. All this in thirty minutes. What kind of work do you think he is giving? Bum splices, hasty punch marks. Doubled reels from the factory will eliminate all this half way work and will give the op- erator a little more time to service the sound equipment and do the other work without even having to worry about the feature, as he knows it is already marked for C. O.s In this way he is not excited and can pay more attention to his show and last of all. the producers print is not chopped, punched or mutilated. Mr. Cowan told me that there was a differ- ence in opinion between the projection super- visors of a large chain theatre circuit. That the eastern man was against the doubling practice, that he in a short time would have it stopped. The western supervisor did not object to the practice, and lets his men do it. It seems to me that the eastern man's idea is purely personal, there doesn’t seem to be any foundation to his objection. A check on this could be made by the pro- ducers in this way: "All Quiet on the Western Front" was shipped out doubled. Compare this feature’s ends with that of others, say at a certain length of time on the run. Also exam- ine between 1 and 2 of the reels. As for the Standard Prints I found another flaw and I shall have to refer back to the doubling again. Every time an operator dou- bles he cuts away portions of the leader or print frames. This of course shortens the length of the threadup footage marks. The prints naturally have to be kept in their proper lengths to come out right. In other words, to be treated as a disc print would. But this is not being done here at all. I will say, though, the exchanges are doing their part in keeping the prints right. With kindest and personal regards to you and all the boys, I am fraternally yours, GEORGE J. LANCASTER. i i 1 New York, N. Y., Dec. 11, 1930. Projection Advisory Council, Attention Mr. P. A. McGuire. Dear "Mac" and Gentlemen of the Council: Your letter of November 5th reached me shortly after I read the pamphlet on "Stand- ard Release Print Makeup and Practice.” I congratulate the Council for their part in the endorsement and wide distribution of this pamphlet and the Technical Bureau on this achievement. This is indeed evidence that the Council has emerged from a vague idea of possibilities with a practical reality. When I recall the years of preachment by F. H. Richardson against the butchery of film with 57 varieties of change-over marks, the past indifference on the part of exchanges — even more recently in small theatres — the scratches made on sound film for change-over cues, the "Standard Release Print” is a remarkable, if much needed, advancement in film practice. As my work takes me into the projection rooms of many theatres I will take every oppor- tunity to discuss this matter with the pro- jectionists, get their reactions and advocate their co-operation. Any suggestions I might obtain in this matter I shall be glad to pass on to the Council. Sincerely yours, (Signed) ARTHUR R. SCHULZE, RCA Photophone, Inc. Academy Officials Discuss Standard With Projectionists . . . Lester Cowan, S. J. Twining, Don- ald Gledhill and Sidney Burton of the Academy Standards Committee called an informal meeting with several leading Los Angeles projectionists on the night of February 5th. The pro- jectionists who acted as an advisory board were Magnus Nielson, Ray Haskell, A. C. Schroeder, Fred Hum- phrey, Jessie Grayson, Bob Babcock, Fred Weaver, Willard H. Fife and D. H. Koskoff. The editor was invited to represent the Loudspeaker at the conference. Standard Release Print Discussed The various phases of the Standard Release Print was discussed at length. The first question asked by Mr. Cowan was whether or not the projectionists approved of the size of the black dot. After an exchange of opinions a vote was taken and it was unanimous that the dots should be reduced between a third and a half of their present size. Location of Dots The next question was whether or not the projectionists approved of the location of the dots. Several loca- tions were suggested, but the concen- sus of opinoin was that they should be placed in the lower right hand corner instead of their present loca- tion in the upper right hand corner. The principal reasons offered for this was that they would be less conspicu- ous in this new location and that they would have less chance of showing in characters’ faces. It was pointed out that this condition has occurred several times since the standard was adopted. Change in Safety Footage Suggested The present standard allows one foot of film for safety after the douser cue has gone through. It was decided that for absolute safety this space should be increased to three feet. It was further suggested that this footage should not include any essential dialogue, but that it should include non-essential sound. This latter would prevent the freezing ef- fect of no sound at all. Reel Lengths Discussed Considerable time was spent on the subject of reel lengths. Mr. Cowan pointed out that the circuit chiefs in the United States are not agreed on whether single or double reels shall be used in their theatres. One of the largest circuits in the East insists that their projectionists run their shows on single reels. At the same time an equally large circuit in the West encourages their projectionists’ practice of doubling. The assembled projectionists were about evenly di- vided in t^eir favor for one method over the other. Ray Haskell brought out many interesting points regard- ing the economies to be effected by the adoption of the double reel length as a universal practice. Better Understanding The meeting was a very profitable one to all concerned. The Academy representatives gained a fairly work- able idea of the way the projection- ists in Los Angeles are reacting to the Standard Release Print. The projec- tionists gained a fair idea of the mag- nitude and complexness of the prob- lems being considered by the Stand- ards Committee. Nineteen Give the Musicians a Break By J. B. G. The writer is not a musician. He can’t whistle, yodle, hum or other- wise carry a tune. And all he knows about notes is that he shouldn't sign them. His only contact with musi- cians has been with those who are employed in theatres. He has, as have other projectionists, made “cracks” about musicians that have not been compatible with the fact that both of the professions are inter- nationally affiliated. The “cracks” were always personally aimed and not generally, and were based upon the axiom that some of the har- mony dispensers are at worst, ex- esperatingly tem- peramental; though at best, extremely fine chaps. Before the ad- vent of sound pic- tures and the pro- jectionist’s subse- quent increase in remuneration, a projectionist was too often a conceited operator; while an operator was merely a nonde- script, good-enough-egg, who invari- ably transferred oil when shaking hands. The musician earned a rather fail- salary and while no one carrying a card begrudged it to them, it would not be strictly honest to say that com- parisons were not made and that these comparisons were not conducive to a foolish though potent bit of jealousy. It seemed that the two pro- fessions were figuratively as remote as the screen from the projection room and the number of feet in the program. Yet they were hopelessly bound, inseparable, each utterly de- pendent upon the other for a perfect presentation. Then the talking fools walked where the silent angels feared to tread, and the sound opuses were upon us, with us, and part of us. The younger projectionists were jubilant, the older projectionists skeptical, while both the younger and the older musicians were captious, angry. As would be you and I ! During the first months of sound many petty altercations ensued, dur- ing which the “I’m for sound’’ men clashed with the “I’m against sound” men, with no men lost and but a few bad optics. The musicians, how- ever, silently watched the box office receipts and knew the election returns early. In fact, before many of us had a chance to even stuff the ballot boxes. A piti- fully large num- ber of their mem- bers were crowd- ed out, their thousands of dollars spent for les- sons, their long years of study, their high hopes of a future, futile, dimmed and fading. They took it gamely, nervily, weld- ed together like true brothers in mak- ing the fight of their very existence. They are still making it. Every pro- jectionist personally knows musicians who have been hit and hit hard ; mu- sicians who a few brief months be- fore were on top of the world, but who are now counting off the days of a two weeks’ notice and racking their brains to figure how to pay the next month’s rent. Gloating has been done, but it hasn’t been done by the projection- ists. Occasional exhibitors have (Continued on Page 26) It is with greatest pleasure that we here present the finest specimen of 'projection minded’ material that has yet come to our attention. We add our hearty approval to the subject matter of this article. It comes to you from the pen of J. R. Q. of Oakland, California, whom you will all grow to know and admire, as we do, for his splendid idealistic attitude toward his profession and the close knit world in which we projectionists live and move. Read this article... think about it... then read it again. ... It’s big — editors. Tnven ty AUTO TRANSFORMERS Auto-transformers are a type of transformer in which part of the winding is used as the secondary, but only a part of it is used for the pri- mary. This gives a step-up ratio. Auto-transformers are sometimes thought of as a variation of imped- ance coupling, and the auto-transfor- mer is the result. The tap is placed about 2/3 or 3/4 the way up, thus giving a step-up of about \l/2 to 1. °Jiq 1 In some respects the auto-trans- former is similar to the transformer and also to the impedance type of coupling. The primary has a very high impedance, which is a requisite for quality reproduction. The sec- ondary being larger than the primary causes the increase in voltage ap- plied to the following grid . The volt- age gain is not as great as it is in the regular transformer, but this is not serious, as resistance or imped- ance coupling produces no gain other than that derived from the tubes. As some of the best audio transformers have a ratio of only 2 to 1, the auto- transformer makes a pretty good showing. The music produced by auto-trans- formers may be as good as that pro- duced by other forms of coupling. The type of coupling is not the all- important thing. At one time it was thought by many that no other form of coupling could approach the qual- ity that resistance coupling gave. The present day transformers have changed that, and now there is little difference between the two types. Going back to the Clough trans- former again we see that it is really an auto-transformer. Forget the re- sistance and the condenser. Then we see a coil with three terminals, one at each end and a tap near the lower end. The ratio of the Clough trans- former is greater than that of the or- dinary auto-transformer. ■Western Electric uses an auto- transformer between the second and third tubes in the 8-B amplifier. Look- ing at Figure 1 it is seen that the wiring resembles that of the Clough transformer very much. In place of the resistance a choke coil is used. This is called a retard coil. The choke serves the purpose that a resistance would, that is, the result is the same, but the manner in which it works is different. T to 1 megohm as a rule. A few years back the values were lower, sometimes 100,000 ohms being used, and not very often was the resistance greater than >4 megohm. The purpose of the low values was to stop “motor- boating,” a form of low frequency oscillation caused by feed-back. For a time the cause of the trouble was not so well understood. It was thought that the tube was blocking, that the electrons were gathering on the grid faster than they could leave via the grid leak, so a leak of smaller resistance was substituted and the trouble disappeared. This, however, caused a loss in amplification, espe- cially at the low frequencies. Later it was learned that the real cause was feed-back from one circuit to some other circuit preceding it, so steps were taken to isolate the various cir- cuits. This is accomplished by fil- tering all the grid and plate circuits, which means that the signal currents in any one circuit are kept there and are not allowed to flow through a common impedance, usually the B T ive n ty -tnxi o supply, setting up a voltage across that impedance at the signal fre- quency, thereby impressing the am- plified signal back on the first tubes of the amplifier and thus causing the “put-put” known as motorboating. Now let us get an idea about this filtering. Referring to Figure 3, the signal currents in the last amplifier tube, after passing through the trans- former, are shunted back to the fila- ment by a condenser; an impedance, such as a choke or a resistance, is in series between this point and the B supply to hinder the signal in passing on to the supply. In this way the signal is kept from going through any associated circuits where it would interfere with their operation. The other circuits are filtered in the same way. Suppose that Figure 3 now represents the plate circuit of the first stage of the amplifier. If a tendency to feed back were present the varying voltage causing it would encounter the resistance on the way to the plate, which would tend to de- crease the feed-back. Now we come to the condenser, which shunts the remaining part of the interfering voltage to the filament and so to nega- tive B, where it can do no harm. As a result of nearly perfect filtering some amplifiers are now used with grid leaks having a resistance of 5 megohms, and without the least ten- dency to motorboat. Any auto-transformer wired in the conventional manner as shown in Figure 2 can be rewired so that it practically becomes a Clough trans- former. A lower value of resistance is used and it is connected from the plate to positive B, the grid leak hav- ing been removed. The condenser is taken out of the grid circuit and put in the lead from the plate to the tap on the transformer. The same thing can be done with any other transformer. The lead go- ing to the grid of the tube is left as is. The lower end of the secondary is connected either to the plate ter- minal or the plus B terminal of the primary. The end of the primary that has not been used is connected to negative C. Which end of the pri- mary to connect to the lower end of the secondary must be found by trial, the connection giving the greatest volume is the one to use. The coils are then connected so that they are in phase. A resistance is put between the plate and the B supply and an isolating condenser connected from the plate to the junction of the pri- cTi e n ty -si x A projectionist couldn’t do his best if patrons sporadically held their hats in front of the projection ports, or playfully tossed lighted fire crackers into the projection rocm. No moie so can a musician do his best en- sconsed a few feet from horns which do not go into action at the same in- stant every performance. Give the musicians a “break”! It’s like putting money in the bank. And possibly when the youth tentatively christened “Television” grows into manhood some of our wails for a “break” will be heard and answered. And possibly all of us won't have to sell papers — or cigarets — or unem- ployment apples — or worse yet, be- come managers! i 1 1 CHARACTERISTICS OF H. I. ARCS (Cont'nued From Page 12) a decided peak of energy in the blue and near ultra-violet end of the spec- trum. This tail flame and negative arc stream light is not picked up by the optical system commonly used in either the Sun Arc or projection lamps and is not therefore a factor. It would seem from these energy dis- tribution curves in Fig. 7 that the high intensity arc, particularly at the higher currents, is a very desirable light source for use in motion picture photography. An example of the use that can be made of data of this nature is fur- nished by comparing the relative light which can be obtained on the screen when 13.6 and 16 milbme'e ■ carbons are used with the ordinary plano-convex lens combination. If the 13.6 millimeter carbons were to be burned at 120 amperes and the 16 millimeter carbons were to be burned at 145 amperes, the crater areas (Fig. 5) are 90 and 137 square milli- meters and the intrinsic brilliancies are 737 and 620 candle power per square millimeter, respectively. It has been shown in the Transactions12 that for crater areas of 137 square millimeters the relative screen illu- mination with arc and lenses set PORTABLE SOUND (Continued From Page 8) throughout, strong AC line noises and other detrimental effects leaked in when the P. E. C. amplifier was incorporated in the same case with the main voltage amplifier. The en- gineers finally segregated the P. E. C. emplifier from the main voltage am- that they can be isolated during op- eration but put into one case for handling. They can be instantly hooked together as shown in the pho- tograph, by means of the flexible de- tachable plugs and cords. The P. E. C. amplifier case contains the input stage of 224 and its asso- ciate stage 230-test jacks and meter, etc., the plate of the 230 connects through the connecting cord to the main voltage amplifier. The main voltage amplifier consists of two stages of push-pull amplifica- tion and also the full wave rectifier, filter system, volume control, test meter and jacks. The reason for using two stages of push pull is the exceptionally low AC hum and the large amount of un- distorted output derived from its use. The reader will notice that we use the ux210 or 310 tube in the output amplifier. The reason for this is that our experience with 250 and 345 tubes for this type of work has not been satisfactory. In talking picture properly is approximately 27 per cent more than for a crater area of 90 square millimeters with two sources of the same intrinsic brilliancy. After correcting for the difference in in- trinsic brilliancy, it is found that only 7 per cent more light can be expected from the 16 millimeter carbons at 145 amperes than from the 13.6 milli- meter carbons at 120 amperes. Such calculations as these, which are made possible in part by the data given above, should be of some assistance in the more efficient use of this very fine source of light for projection of all kinds. reproduction any barrel distorted re- production is met by the average listener with disfavor. Accentuation of the bass is detrimental. What is needed most are frequencies in the voice range and accentuation of the higher range. This has been done very satisfactorily. In locations where 110 volts AC is not obtainable, but 220 or 440 is handy to attach to, a step down trans- former can be secured for reducing the voltage to its proper value. In case DC is the only supply avail- able the equipment can readily be used in conjunction with a small DC converter. This makes it possible to use this system readily on trains, boats, etc., where no other type of electrical energy is available. There will no doubt be in the near future considerable use of the vari- ous types of portable sound appara- tus. They are particularly suitable for use in churches, schools, cafes, dance halls, private homes, etc., where temporary installations are desirable. It is therefore extremely fitting that every projectionist should have a working knowledge of this as well as the other systems on the market. 1 1 i STRIP GEARS ON 707-A DRIVES If you should have a case where fibre gear on 707-A Drive is stripped and a disc show is being run, the 707-A Drive may be removed and film threaded through film com- partment of 1-A Sound Unit. When removing this 707-A Drive, the 700-A Aligning Tool should be insei’ted in place of 707-A Drive in order to hold castings of universal base in place. However, if you do have a film show and not over three teeth of this gear have been stripped, the 707-A Drive may be left in providing the bevel gear on 708-A Drive is set just be- yond where these teeth are torn out. 707-A Drive will then obtain enough momentum in one revolution to ride over these broken teeth of gear. Twenty - seven THINGS IN GENERAL By THE EDITOR Retrenchment Necessary Now that the requiem for wide film has just about died out and the last lingering fragments of that “re- volutionary idea” has been safely buried we are looking for the next development that will occupy the at- tention of the producers, projection- ists and theatre owners. Television is still in the short pants stage of de- velopment with no prospects of reach- ing the commercial stage of develop- ment necessary for theatre use for many years to come. Optical projec- tors using no intermittent movement were widely exploited for years. There was a projector manufactured in Germany which was good enough to attract considerable attention in America. It was known as the Mechau and received a trial in Amer- ica, but was finally discarded as im- practical. In short, the story is that tremendous sums of money have been spent in chasing wild ideas up long dark alleys from which said ideas never emerge. It seems that an al- most limitless amount of money is always available to promote any idea which sounds reasonably plausible whereas some of the smaller yet more important things are consistently ignored. For example, a performance per- fectly presented with reasonable em- bellishments such as organ solos, acts, overtures, etc., and capably handled by real conscientious projec- tionists who really make the best of the more or less ordinary equipment of the average modern projection room, will attract and satisfy more patrons than all the wide screens, optical projectors and similar innova- tions ever invented. It is not meant to infer that it is not advantageous to increase the size of the picture for panorama out-door scenes. This is T iv e n ty - e i g h t most effective and is accomplished by the simple expedient of changing to a shorter focal length lens at the pro- jector and cannot possibly be com- pared with the exceedingly expensive wide film systems. It occurs to us that much can be done to better please the patrons without huge expenditures of money. A brighter, clearer picture that is steady on the screen and focused ex- tremely sharp seems to be a small order, yet many theatres lack just that and at the same time contem- plate large expenditures of money for wide screens, wide film projec- tors, etc. Our point is: Let’s get down to a fair degree of perfection in presenting film subjects and stage presentation before wildly searching for newer, faster ways of spending money. — o — Appeal to Westerners It is the desire of this publication to be of service to each individual projectionist in the West. It is im- possible, however, for a member of our staff to be present at each meet- ing of each A. P. S. Chapter in the West. It follows, therefore, that we must depend upon the members of each chapter for our information about their chapter and its members. We believe that the western projec- tionists will combine to make their Loudspeaker the outstanding craft publication in America. Send in that story or news item today. Learn to laugh. A good laugh is better than medicine. Learn how to tell a story. A well-told story is as welcome as a sunbeam in a sick room. Learn to keep your own troubles to yourself. The world is too busy to care for your ills and sorrows. Bro. Frank Sawyer and members of the editorial staff of this magazine visited the regular meeting of Chap- ter 19 at San Bernardino at its meet- ing of January 27, and were royally entertained by the officers and mem- bers. After President Reynolds called the meeting to order things began to happen in rapid succession. First — Feed (of banquet proportions), sec- ond— business, third — a red hot lec- ture on amplifiers by Mr. N. P. Minor of E. R. P. I. closed the peppiest meeting we have attended in a long time. i i i Bro. Fowler is still wondering what became of the trick hats and whistles at the Dinner-Dance. i i i An emergency benefit baseball game will be played between Dawn Post and Maywood Post, American Legion, baseball teams at Wrigley Field. The day is Sunday, March 8, at 2 p. m. Prior to the actual game an entertainment will be given featuring the American Legion Band. Many stage and screen celebrities will be present. Wrigley Field admission prices will prevail. i i i After an absence of fifteen years, a projectionist recently returned home to his wife. Evidently he had suc- ceeded in thinking of a new and ori- ginal excuse at last. A new member was ushered into California Chapter No. 7 at the meet- ing January 20, 1931. The fortunate man is Bro. Alonzo S. Bennett of Long Beach, Calif. Bro. Clarke Searle, also of Long Beach, was present to see the job well done. From SAN BERNARDINO, CALIF. Resistance Coupled Franklin from Riverside is still trying to find out what to do with the ash can. i i i Brother Bill Moes of Pomona has developed a large German goitre. No he’s not sick — his chest slipped. i 1 i Paul Tuggy, radio technician of Riverside, gave Chapter No. 19 a very educational lecture on vacuum tubes at a recent meeting. Mr. Tuggy is well known as an authority on this subject and his lecture was very much appreciated by the membership. ill We unanimously elect Bro. A. L. Hanson to the position of champion sleeper of the world. i i i Chapter 19 has just started a library for each of its members. The first acquisition was a copy for each of Radio Telegraphy and Telephony by Duncan & Drew. Several other books are being considered by the chapter for purchase in the near fu- ture. T njo e n t v - n i ne I, hapier Doings Californ ia Chapter Number Seven R. C. A. PHOTOPHONE LECTURES THIS MONTH The first meeting in March will be held in the T. V. G. Building, 936 West Washington Boulevard, at 12:00 midnight, Tuesday, March 3, 1931. At this meeting Mr. Watson Jones of the R. C. A. Photophone Corp. will deliver the first of a series of lectures on R. C. A. Equipment. Don't miss this first lecture of this important series. Preceding the lecture the usual lunch will be served in the Rathskeller. The second meeting in March will be held in the same hall at 12:00 midnight, Tuesday, March 17, 1931. This will be an educational meeting. The second lecture by Mr. Wat- son Jones of R. C. A. Photophone Corp. will be delivered a<: this meeting. Lunch and social hour before the meeting. Members of other chapters are cordially invited to join us at either of these meetings. San Bernardino Chapter Number Nineteen San Bernardino Chapter Number 19 meets at the American Legion Club House, 1 1 3 West E Street, On- tario, Calif., on the second Tuesday of each month at 12:00 midnight. Dinner is served after which a short business session and educational lecture are provided. A real worthwhile evening is always provided for our members. Visitors from other Chapters are cordially invited to break bread with us and enjoy our meetings. Thirty CALIFORNIA CHAPTER NO. 7 It is indeed gratifying to be able to announce the “main event” for coming Society meetings. Through the efforts of President Bur- ton and his co-ordinates the services of Mr. Watson Jones, resi- dent R. C. A. representative, have been obtained for a series of talks on photophone recording and reproducing equipment. Air. Jones is recognized as being one of the leading sound technicians in the in- dustry and the invaluable data which he has to offer should prove a real treat. The Society is greatly indebted to those organizations which have co-operated so wholeheartedly in offering us such splendid speakers, men outstanding in their chosen branches of the profession, and it is indeed a rare privilege to meet these men face to face and share the fruits of their hours of study and research. We, here in the heart of the picture industry, do not fully appreciate the advantages of- fered us. We are at times inclined to be a trifle lax in availing ourselves of the opportunity of obtaining first hand information from those devoting their efforts to the betterment of the art of talking pictures. The series of talks offered by Air. Jones will not deal with the elements of sound, tubes, their functions, batteries, and the like, but will be devoted to detailed explanation of the Photophone equipment. Each talk will feature a definite part of the equipment and when pos- sible will be demonstrated by actual contact with the particular phase of the system under discussion. The first of these lectures is to be held Tuesday, March 3rd, and of course will be preceded by the usual repast in the Rathskeller. May I suggest that each and every member of the Society make a special effort to attend this, and every meeting of the series and reap benefits to be derived from it. Thirty - one ACADEMY EXECUTIVE SPEAKS IN OAKLAND Mr. Clinton Wunder, executive manager, Academy of Motion Picture Arts and Sciences, spoke at a lunch- eon of the Oakland Chamber of Com- merce Friday noon, January 16th, 11:15 a. m., at the Athens Club, Oakland. Practically all the theatre managers in the East Bay theatres were represented. Several acts from the R. K. 0. Orpheum and Fox Oak- land theatres lent their talents for the entertainment. On Mr. Wunder’s right at the speaker’s table was seat- ed Frank Seavier, representing the A. P. S., and on the left. Geo. J. Lan- caster, representing the P. A. C. Mr. Wunder’s message was one of great promise of the continued suc- cess of the motion picture industry. The following are some of the high lights of his address: His prediction is that talking pic- tures are here to stay for ever. He pointed out that the motion picture industry is the fourth largest indus- try in the United States and employs more people in all its branches than any other single industry of its size. The consistent popularity of motion pictures is due to the real service they perform for civilization. To illustrate this Mr. Wunder pointed out that many foreign people are learning the new Hollywood dress, fashions and speech from the screen. Another example of service was an incident in a certain South American city where a popular American made automobile increased its sales in that city because a film was shown with an automobile race and this car was the winner. Another case was in an American city when a strike closed all the theatres for several days. There were scores of holdups and burglaries that were attributed to the fact that the public had had its enter- tainment cut off. The crime wave stopped when the police chief ordered an immediate settlement between the exhibitors and projectionists so that the people would have some place to go. Mr. Wunder stated that many cities in this country have recognized the value of sound motion pictures for educational work and have estab- lished departments to be known as the Department of Visual Education. These departments are functioning perfectly and are a great aid in pre- senting educational subjects.' Mr. Wunder closed his very inter- esting talk by stressing the fact that the Academy was anxious to work with the American Projection Society and the Projection Advisory Council in promoting their mutual interests in the industry. i i i “What kind of a dress did May wear to the party last night?” “I don’t remember. I think it was checked.” “That must have been a real party.” EP FOr get YOUR t»ouBl USE BlEs / A * Visitron Type JA‘ Photoelectric Cells Longer Life Higher Sensitivity Less Background Noise Better Sound Reproduction and ... NO TROUBLE • The Cell with six months guarantee U'rite for Information GHN LABORATORIES flNC It CHICAGO. U. S. . ^ El-*-*-*— • *■*■*■+■■**■■**■*■*■■* ^ Thirty-t^wo Thoughts While Stalling Apologies to O. O. McIntyre Some pictures I would like to run again .... A Woman of Paris, the only serious drama ever produced by Charles Chaplin. It concealed in real human fashion the peaks of emotion. It was at least fifteen years ahead of its time .... Lewis Stone in River’s End, a silent picture which literally screamed dramatic art .... Pola Negri in Passion, a colored produc- tion from Germany that made history ten years ago .... Chaplin and Coo- gan in The Kid, human interest and pathos never excelled either before or since .... Marie Dressier in Til- lie’s Punctured Romance, a marvel- ous example of the mugging type of humor .... Mabel Normand in Micky, the picture that printed her wistful smile indellibly on the hearts of mil- lions of picture fans .... Pearl White in The Iron Claw, a serial thriller that really thrilled. Even the sophis- ticated elders followed each chapter with breathless expectancy .... Ford Sterling in His Great Moment, a style of comedy now gone, but very popu- lar at the time .... Douglas Mc- Lean in Going Up, the climax in a flight that made your hair stand on end never failed to bring the audience to the edge of their seats .... Quo Vadis, produced by the Italian com- pany of Ambrosia, was a picture with a huge cast well handled by compari- son with other attempts at that time . . . . the Desperate Desmond series produced by Nestor. — o — Actors and actresses I’d like to see again .... Katherine McDonald . . . . Mary Fuller of the Edison Co. . . . Marguerite Snow, James Cruze and Florence La Badie, the eternal tri- angle of the old Thanhauser Co Marguerite Fisher, J. Warren Kerri- gan and Jack Richardson of the American Co “Our Mutual Girl” who popularized the products of the Mutual Film Corp Irving Cum- mings in Comet Comedies .... John Bunny, Flora Finch and Lillian Walker of Vitagraph. These stars shown brightly and then flickered out while most of the projectionists of the present day were still in their swaddling clothes cooing at their proud parents. Projection is the only profession in the world wherein a man can be an old timer at thirty. NATURE OF LIGHT (Continued From Page IS) fringes. There are others visible with slits, circular aperatures, discs, stripes, etc. When white light is used the bands are colored due to the unequal bend- ing of light of different wave lengths. The source of light must be small a slit or a spot, for diffraction fringes to be observable. If the source is too large we have fringes from each point of the source overlapping until in- distinguishable. The colored rings around the sun or moon when seen through a thin cloud are due to diffraction. We can sometimes see diffraction fringes through our eyelashes. Scientists have one important ap- plication of diffraction. It has been found that strips of opaque and transparent material separate light into spectra. This effect was first se- cured by the use of wires so the ap- paratus was called a grating. Now the diffraction gratings used are ruled on glass or speculum metal and commonly have about 15,000 lines to the inch. The work of analysis of ultra violet and infra red spectra is carried on using gratings on metal in which the diffraction is secured by reflection. (To Be Continued) Thirty-three LOUDSPEAKER FOR WESTERN PROJECTIONISTS Sponsored by California Chapter No. 7, A. P. S. A. L. FEINSTEIN, ■ Circulation Manager, \ 2432 Cloverdale Avenue, 1 ; Los Angeles, California. Kindly enter the following subscriptions to the Loudspeaker ; at $1.00 a year. ; (This rate applies to 5 or more subscriptions) Name • Address ] • Town State , ‘ Name . Address 1 ’ Town State • Name ■ Address Town State Name ] ■ Address < ' Town State . Name , Address < ' Town State ] Enclosed please find $ for subscriptions ; The rate for individual subscribers is $1.50 a year, single copies 25c 1 Changes of address must be in the fifteenth of the month previous to the . date of publication of the issue on which the change becomes effective. , ; BE SURE WE HAVE YOUR CORRECT ADDRESS. ; Thirty- four Condenser System for Wide Film by EUGENE H. ROONEY (Reprinted from Projection Engi- neering, this being in our opinion vital information to every projec- tionist.— Editor). The recent success of wide film and its probable adoption by the motion picture industry now brings to light a most perplexing problem. Consid- ering the new standards of screen size and the change in film aperture to 1 :2, it is more difficult to obtain a brilliant and uniform screen illumi- nation free from chromatic aberra- tion and ghosts. Until last year the condenser sys- tem available consisted of a pair of piano convex lenses of different di- ameters and focal lengths. The most light thereby obtained on the screen with the use of one of the best high intensity arc lamps amounted to about 5,500 lumens. It is a known fact that a parallel beam of light overcomes distance more efficiently. This thought caused the use of parabolic condensers. Since the film window is rectangular, the projection of a round spot means a waste of light. A full spot cover- ing all four corners of the rectangu- lar window was finally developed by means of grinding a horizontal curve on one side of a condenser, thereby broadening the beam of light in one direction. Steps were also taken to increase the amount of light emanat- ing from the arc, in other words, the collecting angle was enlarged. After the above tests and exten- sive research work in conjunction with both foreign and domestic op- tical firms, the Fish-Schurman Cor- poration of New York finally pre- sented a special condenser system for wide film projection. This system consists of : one 5 Yz diameter Grand Special A cylindrical, spherical, bi-convex and one 6" diameter Grand Special B parabolic, convex-concave. It is made of genuine optical glass and the amount of light is increased to about 10,000 lumens to 15,000 lu- mens compared with the 5,500 lumens for the old system. Considering the extreme heat to which a condenser is subjected, it is essential that it be made of special heat-resisting glass like IGNAL, which defies the heat and represents the best type of genuine optical glass. The arrangement of the S. O. G. Condenser System, as seen in the il- lustration, is carried through as fol- lows : Grand Special A is placed with its cylindrical curve about 3 y2" from the arc, its two marked lines in a horizontal position. Grand Special B is placed with its concave side as close as possible to the spherical con- vex side of Grand Special A, without, however, touching it. RITUAL EQUIPMENT BUILT A problem to many chapters has been solved by Bro. C. D. Fink, 572 Burdick Drive, Pomona, Calif. He has built a handsome set of pedes- tals for use in initiation. They are of modernistic design and are well made in every respect. They would be a splendid addition to any chap- ter’s equipment. Any chapter desir- ing these pedestals should communi- cate with Bro. Fink direct. T hirty -fiv e Health Talks For Projectionists Every line of endeavor that ulti- mately led to a profession had a humble beginning. This humble be- ginning might well be termed the nu- cleus of that profession. The pro- gressive stages between these two ex- tremes might well be termed its period of evolution. In all cell life the progress of evolution tends toward a higher plane. Similarly the projectionist is fitting himself for a place among the professional men of the world. The transition is perhaps difficult and there is a constantly increasing demand on his mentality. This in- creased activity promotes growth of ability in that organ of the human anatomy called the brain. In defining the brain we would say that it is a highly specialized differ- entiated nervous tissue, located in the cranial cavity, functioning in co-or- dination and pre-sentation. In this same manner we may define the rela- tionship of the projectionist’s posi- tion to the theatre with the one excep- tion, the location. He, being confined to the projection room. It is in this room that the projectionist does his work in charge of extremely valuable equipment. I propose to write for the western projectionists a series of articles in view of helping them to safeguard that most important piece of equip- ment, the “human machine’’ that in- habits the projection room. The most common diseases that projec- tionists are susceptible to can be traced directly to the closely confined quarters in which he is forced to work. Lack of exercise, tedious nerve strain, poor ventilation, irregular eating, improper rest are all contri- Thirty-six buting factors to the functional dis- orders peculiar to projectionists. By having a general knowledge of the cause and prognosis of a func- tional disturbance one is better able to build up a suitable resistance against that particular disease. It will be interesting to note in passing through this series of articles how similar the human body resem- bles the sound equipment with which the projectionist works. This equip- ment is gone over and kept in a state of health at all times, thereby assur- ing perfect results. The human body should be given the same consideration, for after all the greatest asset one can possess is health, and then, too — the survival of the fittest may be applied — psycho- logically and physiologically. Another article will appear in next month’s edition. RED PENCILS By Frank Erler, A. P. S. A few years ago we called upon the Film Board of Trade to help us get rid of the “punch and scratch” artist and just about had this pest stamped out when sound pictures came in, so some one thought up the idea of the back patch, which was a great idea. Then the “punch and scratch” artist started in again to improve on the back patch, the little click was not enough — he had to have two of them. It does not matter to him if the clicks are already in the reel, he must have his own special color or patch, some covering two or three sprocket holes so they can see the patch and the jump as well. They put it right across the center of the frame. He never gives a thought that the thick patch will soon tear across the sprocket holes and bang goes a nice sound track. Some of us try to pry them off, but the artist cements them on too well. Now we are getting some fancy ones such as the letter Z, keystones, etc. Sound has also put another weapon in the artist’s hand. The opaque lacquer. They now get the reels with lacquer along the sprocket holes and covering a foot of sound track. I suppose when the sound stops it is time to start the motor. Then they dot out the faces of characters in action with lacquer. The red grease pencil is the worst of all. At first it would seem to be 0. K., but one will draw a line near the sprocket holes about eight inches or a foot long. The next will put in a few crosses. Then the good old dots will come along for about eight frames. With all that grease the reel will be rewound a few times and the back of the film will pick up some of the grease and with the heat on the film wound up tight it will smear the sound track and down goes the sound. This happens on film less than thirty SAN FRANCISCO CHAPTER 16 OFFICERS » » » » In our January issue an error oc- curred. The caption appearing over the list of officers of San Francisco hapter No. 16 read 17. This error was called to our attention too late to be rectified in the February issue. The officers for Chapter 16 for 1931 are as follows : President — Frank L. Seavier. Board of Governors — Harry C. Everett, vice president; Frank Cos- tello, Paul O. Gaffney. Treasurer — Walter G. Reinhardt. Secretary — John Ford, Jr. Sergeant-at-Arms — A. E. Murray. Under the progressive guidance of Bro. Frank Seavier Chapter 16 has made steady advancement. More good work is expected during 1931. i i i Ashcraft: “You must separate the condensers by a millimeter.” Vencill : “I tried to, but I couldn’t find a millimeter to put between them. days old, so it must get worse as the film gets a little older. Now, we all thought that the trou- ble would be over when the new Standard Release Print got into ef- fect, but we find the artist is just as bad. In the past month all visual dots were 0. K., but the red pencil is still used as well as the click patch and in one feature a pin scratch was used alongside the visual dots. In two instances the footage numbers were lacquered out in the leader. Pre- sumably the cut-over was made too soon and they showed on the screen so they had to be painted out. Now, with the new Standard Re- lease Print, is the time to teach the artist that his art is not wanted in the projection room of boys who are to put over a smooth show. The film exchanges should be called upon again by a committee from each dis- trict and request them to check where the damage is done and see if it cannot be stopped. Thirty - seven CHAPTER 1 7 CELEBRATES BIRTHDAY Chapter No. 17, A. P. S., which is situated in Seattle, Wash., has just passed its first milestone. It is one year old and is very robust indeed for its age. It has grown from eleven charter members to a membership of thirty-three at its first anniversary. Information comes from Geo. J. Kalushe that several applicants are to be initiated in the near future. This will undoubtedly bring the total mem- bership well into the forties. Seattle is to be congratulated upon its splen- did progress. 1 i i “I hear your son’s at college.” “Yep.” “Pretty good, I guess ; he’s taking three courses. I’ve just paid out ten dollars for Latin, ten dollars for Greek, and a hundred dollars for Scotch.” J'farrv W< enyer PHOTOGRAPHIC STUDIO Portraits and Theatrical Work a Specialty Centrally Located Just Out- side the Congested District Studio Second Floor Film Exchange Bldg., Room 30 Cor. Washington and Vermont Los Angeles, Calif. ■ ALLOY EMBLEMS FOR YOUR CAR APS Emblem, 2%" in diameter, beauti- fully enameled in black and silver,, with attachment for fastening to your radiator. Price $1.00. IATSE Emblem 4" in diameter in blue and silver enamel with attachment for fasten- ing to your radiator. Price $1.00. i i i This emblem can be furnished with any number for $1.50 CLYDE W. SHUEY, 51 Rose Avenue, Venice, Calif. Manufacturer and Distributor T h i r ty -eight a- Western Projectionists ! All progressive projectionists, technicians, service men and engineers should be subscribers and readers of “PROJECTION ENGINEERING” The largest technical circulation of any motion picture publication TELL YOUR FELLOW CRAFTSMAN ABOUT THE GROUP SUBSCRIPTION RATE The subscription rate for individual subscribers is $2.00 a year or $3.00 for two years. The group rate of $1.00 is available to you when 4 or more subscriptions are sent in at one time. For Your Convenience BRYAN DAVIS PUBLISHING CO., Inc. 52 Vanderbilt Ave., New York City. Enter the following subscriptions to Projection Engineering at the $1.00 a year Group Rate. Name Address Town State * Classification Name Address Town State * Classification Name Address Town State * Classification Name Address j Town State * Classification Name Address Town State * Classification *PIease classify subscriptions sent in as follows: M — Manufacturer E — Engineer p — Projectionist Including execu- tives, purchasing agents, plant su- T — Technician D — Dealer or Service perintend ent, Man foreman, etc. BRYAN - DAVIS PUBLISHING CO. 52 Vanderbilt Avenue, r / New York City LS-2 Eh — - - Afl T hi r ty -nine The Ashcraft Air Blast Projection Lamp Current Range 65-90 Amperes Abundance of light to illuminate even the largest screens Manufactured By THE ASHCRAFT AUTOMATIC ARC CO. LOS ANGELES, CALIF. o r ty H- m TPe represent the folio wing manu- facturers of standard theatre equipment and accessories. ASHCRAFT AUTOMATIC ARC CO. Lamps and Parts W. G. PREDDEY Low Intensity Lamps, Aluminum Sound Reels BRENKERT LIGHT PROJECTION CO. Breno graphs, Spot Lamps, Etc. KAPLAN MANUFACTURING CO. Projectors, Parts for Simplex Projectors DA-LITE SCREEN CO. Da-Tone X Screens, Da-Tone Beaded Screens BAUSCH & LOMB Cinephor Lenses, Super-Cinephor Lenses PROJECTION OPTICS CO., Superlite Lenses ROTH BROS. CO. Roth Actodector Motor Generators NEUMADE PRODUCTS CORP. Rewinders, Film Cabinets, Film Splicers MOON M. P. ACCESSORIES Automatic Rewinds, Measuring Machines WEAVER BROS., Automatic Dousers Bio and National Projector Carbons BRECK PHOTOPLAY SUPPLY COMPANY The Big Independent Supply House LOS ANGELES E ■E . . Announcing . . The Companion Instrument to the Cue-Meter THE T. E. S. PRECISION FILM MEASURING MACHINE SPECIFICATIONS: Heavy cast iron base — will not move around while measuring film. Large 64-tooth sprocket — constructed of duralumin — direct connected to counter — no gears. Sprocket supported on two hearings. Frame numbers engraved on edge of sprocket. Counter placed at thirty degree angle — easy to read. Base open under sprocket. When placed over light on work bench allows frame lines to be easily distinguished without removing film from sprocket. THEATRE ENGINEERING SERVICE 144-2 Beachwood Drive COMPANY Hollywood, California For sale by all branches of the NATIONAL THEATRE SUPPLY CO. DON’T 0 U € S S USE CUE-METERS pril, 1931 wenty-five }\yiw mil • Logical Reasons Why National Should Service Your Theatre: /£TNE source of supply — a definite standard of quality, and that ' — r the very best. Everything you need for the mechanical oper - ation of your theatre can he supplied, promptly and with utmost satisfaction through National Service. A nearby source of supply at 30 well-equipped, well-stocked branch stores, with sales and service men always available on short notice, experts TRAINED TO SERVE YOU CONSCIENTIOUSLY, regardless of what your requirements may be. THE PROJECTION ROOM requires careful consideration in any theatre. Sound film projection makes necessary the pro- vision of precision equipment and careful maintenance. National Service features every need for the modern projection room and National Service Alen are on the job day or night to keep the show in operation. Many new and modern improvements for better projection are now available at your nearest National Branch store and a demonstration incurs no obligation. “If it is needed in the projection booth National has it.” National Theatre Supply Co. Executive Offices--92-94-96 Gold Street, New York MAINTAINING QUALITY IS TRUE ECONOMY The International Projector THREE PROJECTORS OR EMERGENCY EQUIPMENT KEPT IN A1 CONDITION IS A SURE INDICATION OF PRACTICAL-PROGRESSIVE SHOWMANSHIP BETTER PROJECTION PAYS tgisnp/er TAe/nterrt&tiona/ /Eo/ectar % International Projector Corporation 90 Gold Street, New York EARNING THE CONFII WEAVER BROS 3 POSITION SCREEN UNI SELECTIVITY . . Can be changed from any setting to another setting instantly. FLEXIBILITY . . Pilot lights signify what position screen is in at all times. COMPACTNESS . . Unit easily mounted on screen frame. SAFETY . . . Heat relays protect the motors from damage. REMOTE CONTROL . . Can be operated from any number of stations desired. ACCURACY . . . Stops the masks in the exact predetermined position. QUIET OPERATION . . Motors cannot transmit vibration to the screen frame. EXCLUSIVELY DISTRIBUTED BY ARMSTRONG STUDIOS 1717 Cordova Street Los Angeles, California lllllil Two E N C E OF AN INDUSTRY MagnasCope screen control switch Wide screen control switch Work lamp switch Stop switch Standard screen control switch mask motbr Side mask motoi Pilot light switches Standard . selector relay Heat relay Top mask motoi Magnascope selector relay Fuses - Top mask motor Reversing switches Top mask motor ^ Outside wiring terminal strip Fuses . Side mask motor Reversing switches Side mask motor Heat relay Side mask motor Electrical interlock safety switch 1 Wide selector relay^ SS^ Work lamp J * ^ , 1 ", 1 P: a^jriiwS Top mask limit 1 adjustments f m i \ .. wPy Side mask limit I yJ^P^adjustments 1 % oh ree ANNOUNCING THE OPENING OF THE Projection Equipment AND Maintenance Co. Quality, Workmanship and Service ALL REBUILT WORK FULLY GUARANTEED NO CHARGE FOR SERVICE MECHANISM DURING REPAIRS Phone or Write L. M. (Louie) WUTKE 3608 Farris Drive WHitney 4652 C. M. (Chuck) FOWLER Culver City, Calif. Phones — or Culver City 3869 A Technical and Educational Publication. Devoted to the Western Projectionist and his Progressive Fellow Craftsman Everywhere. RODNEY T. BACON w G CROWLEY H. E- ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE '264 Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Pleasant 7332 Circulation JAMES B. GILLARD, Oakland Editor FRANK W. COSTELLO, San Francisco Editor 1436 Delaware St. Berkeley, Calif. 1230 Hyde Street, San Francisco Technical Editors: A. C. SCHROEDER, D. B. McGOWN and R. H. McCULLOUGH Volume II. APRIL, 1931 Number 4 CONTENTS Los Angeles Theatre By E. W. Anderson .... 7 Ground Noise Reduction By R. C. A. Photophone . . 11 San Francisco Chapter 16 Entertains Visitors By Frank W. Costello 17 Three Position Screen Unit By Weaver Bros. ... 19 Celestial Control By J. B. G 20 Cell Voltage Control for Sound-Film Apparatus . 23 Just How Clever Are You? By R. E. Clark .... 24 Craft Technical Data By A. C. Schroeder .... 25 Things in General By the Editor 28 Pin Spots 29 Chapter Doings — California Chapter No. 7 and San Bernardino Chapter No. 19 30 Secretarial Comment — California Chapter No. 7 31 Oakland Meeting Full of Action 35 Published Monthly, Sponsored by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Blvd., Los Angeles, California 71/ we <*> ra a ^ BLUE SEAL | MECHANISM SUPPORT BRACKET Eliminates All Vibra- BLUE SEAL PRODUCTS CO., INC. 266 Wyckoff Street Brooklyn, N. Y. Manufacturers of Motion Picture Accessories Since 1913 > • « 4 tion in the Machine and assures a Steady Pic- ture on the Screen. ADJUSTA B L E T O PROJECTION AN = QLES. STA N D A R D EQUIPMENT ON THE LARGEST THEATRE CIRCUITS. List Price, $15.00 SEND FOR CATA- LOGS AT YOUR DEALERS OR DIRECT IMPROVE YOUR SOUND * < With < \ The Fox Electro - Dynamic Unit : < This unit will stand an ] input of 25 watts con- tinuously. • The voice coil is . wound directly on dia- phragm thereby elimij ] nating coil mountings which have been the chief cause of trouble ] in other units. Voice coil is self cooling and ] will not burn out. Unit . fully covered by pat- ents issued and pend- ] ing. ■ FOX ELECTRIC & MFG. CO. < 3120 Monroe Street Toledo, Ohio Handsomely finished and thoroughly de- pendable over a wide frequency range. Some valuable terri- tory still open. We also manufacture com- plete sound on films and disc equipment for sound pictures. Write us today. Los Angeles Theatre’s Remarkable Equipment » » » By E. W. ANDERSON, A. P. S. The Los Angeles Theater opened its doors to the public on January 30th, 1931, forty months later than the opening of the Tower Theater, which was the initial permanent sound installation on the west coast. Forty months ago the Tower Theater could boast of having the lat- est in projection room layout and equipment. Today every piece of pro- jection equipment is obsolete, due to new developments in projector heads, bases, lamps and amplifying panels. Today the Los Angeles Theater, a two million dollar investment, inde- pendently owned and operated by Mr. H. L. Gumbiner, the man who had the courage to introduce sound to the West, possesses unquestionably the most efficient projection equipment in the world. Where it will stand in the scale of efficiency forty months hence is hard to guess. Three Super - Simplex projector heads mounted on Universal bases, in front of Ashcraft Super High Intens- ity lamps comprise the picture equip- ment. For lighting the stage from INTERIOR LOS ANGELES THEATRE PROJECTION ROOM Seven the projection room, there is an Ash- craft High Intensity Flood, two Hall & Connolly high intensity spot lamps and a Brenkert F-7 Brenograph equipped with Ashcraft high intens- ity lamps. In order that an uninterrupted sup- ply of current may be had there is a Westinghouse 110 volt, 300 amp. gen- erator driven by a 220-volt 3-phase motor with a throw over switch with service from two power houses. Di- rect current is also available from the power company thus giving three sources of D. C. power. House light- ing is also protected by service from two plants. All projection machines, spots, flood and Brenkert effect machine, are on double pole contactor switches of ample capacity. Shunt resistances are also on contactor switches equipped with time limit relays so that in case the projectionist neglects to kill the shunt resistance it will automatically cut out at a predeter- mined time. Projection machine mo- tors and Weaver dousers, with which all machines are equipped, are also on contactor switches. Arc and shunt buttons for each lamp are located not only in each of the six control sta- tions, but are mounted at the base of the lamp house as well. A volt and ammeter for each lamp is mounted on the front wall by the lamp which it meters. There are six control sta- tions, one beside each machine, with pilot lights covering every switch in the station. Each control station is also a fader station. Projector sta- tions each have cue-meters. The amplifying equipment for this theater cost about $50,000. Due to the size and nature of the installation it was a time and material contract. The amplifying panels consist of three 41, four 42 and four 43 panels. There are also four 200 A out-put panels, one volume indicator panel, an amplifier for the deaf sets, and a port- able non-sync table. There are twenty-two horns in the house. Six are screen horns, the re- mainder being distributed as follows : Eight One in each of the cry rooms, two at the entrance of the theater, one at the small screen in the lounge, four cov- ering the auditorium for re-enforce- ment and announcement use, two at the marquee, two in the foyer, one in the main lounge and one in the broadcast room. Sound volume may be controlled from a station located at the rear of the auditorium or the rear of the first balcony. On premiere showings a projectionist is stationed at one of these faders in preference to projec- tion room monitoring. A small rocm adjacent to the pro- jection room contains two motor gen- erator sets with their filters which de- velop the D. C. for speaker fields, ex- citer lamps, and PEC amplifiers. One motor generator is 50 cycle, the other 60 cycle, each served by a different central station, thus insuring continu- ous service as they are on throw-over switches so that either or both may be used. Located adjacent to the projection room is a sound observer station. A large port enables the projectionist to gauge the sound. This little room has its own monitor, is equipped with a three-position mixing panel and one master mixer, a patching panel into which comes sixteen microphone cir- cuits any three of which may be used at one time. Besides the signaling system between the broadcast and this station there is a direct wire to KMTR broadcasting station. Broad- cast may be picked up from the stage, foyer, street or from the theater’s own broadcast studio located adja- cent to the intermediate lounge. An- nouncements over the P. A. system may be made from any one of these stations. Any public address system panel may be transposed with a like sync system panel in case of trouble by means of its key, thus making the en- tire amplifying system proof against shut-downs. The new Los Angeles Theater is the first theater in the world to be equipped with the new Westinghouse CLOSE-UPS OF PROJECTION ROOM LOS ANGELES THEATRE Panels c~ ■ HHHH Control Station Film Cabinet and Rewind Bench MainD.C. inohouse Control Board remote lighting control in which re- covers both stage and auditorium, actance is used in place of resistance The house lighting control board is for dimming. This equipment, in- located in the projection room. It stalled at a cost of about $30,000, was originally intended that the pro- N in e jectionist should operate it, but juris- diction was granted to the Stage Hands Local, hence a remote control station was placed on the stage and stage hands now operate it, although all presets must be made on the mas- ter board located in the projection room. By the use of reactance in place of resistance as a dimming medium it is possibly to preset light intensities and maintain a constant color tone during the entire dimming operation. In the resistance type of dimming where it is necessary to dim one color until the dimmer shaft interlocks with that of another color, to be dimmed, the color tone changes. With the reactance type of dimming, re- regardless of the volume of light at which any color may be preset, the dimming of all selected colors takes place simultaneously and the color in the theater remains the same throughout the entire operation. The reactance of the different cir- cuits is controlled by the degree of magnetic saturation of the core of the reactance coil of each circuit. This degree of saturation is controlled by a potentiometer located on the master board for each circuit. These pre- set potentiometers receive potential from a 48 volt D. C. generator and each potentiometer may be set for any desired intensity of light by mov- ing its contact arm along the winding obtaining full intensity at one end and black out at the other, and any intermediate value by a correspond- ing setting of the potentiometer. The contact arm is connected through the scene selector (this is a five-position board) to the grid of a control tube (a UX 226) which in turn operates on the grid-glow tube in the same cir- cuit. The grid-glow tubes receive their power from the 110-volt A. C. lines and their rectified output is put through the D. C. coil of the react- ance dimmer. This new system introduces the vacuum tube into theater lighting control and will be dealt with more fully in this magazine next month. The entire remote control for this board is enclosed in a small panel on the stage. The selection of presets, speed of changes, black outs, etc., may not only be operated by a variable speed motor from this station, but each color may be operated manually as well. In this panel are five scene- flasher buttons, by means of which any one of the five presets may be operated instantaneously. Blackout of either house or stage is accom- plished at the pressure of a button. For ease of handling, low operating cost, beautiful lighting effects, and every point by which theater lighting control may be judged, this equip- ment is in a class by itself. Adjoining the projection room is the film room and motor generator room containing the generator for the arcs and the four smaller generat- ors for the reactance dimmer equip- ment. The film room contains two steel cabinets for lenses and spare parts, film storage cabinets, steel work bench and ample space for car- bon storage. All rooms of the projection depart- ment are supplied with washed air from the Carrier System and rein- forcing this ventillation is a booster fan to take care of the intake ; a sep- arate exhaust system for the rooms; a separate exhaust system for the lamp houses, and a blower system piped to each machine for cooling apertures, slides, colors, etc. There is an outside door leading to the fire escape and two windows in the projection room. An outstanding innovation in this Theater Remarkable is a reproduc- tion on a screen 33 inches by 44 inches, in the main lounge room of the picture being shown in the audi- torium. As this small screen has its own horn, it is possible for those pa- trons of the theater waiting in the lounge to see and hear at this small screen the same picture that is being shown on the large screen in the main auditorium. This optical develop- ment was designed by Dr. Francis G. Pease, a noted American physicist, (Continued on Page 32) Ten Ground Noise Reduction R. C. A. Photophone System 'RALPH H. TOWNSEND Ever since Thomas Edison made his first sound recording on a piece of tinfoil, reproduced sounds have been what we might call “victims of circumstances.” This is true not only of phonograph disc reproduction, but that from film as well. Always has the listener been compelled to hear reproduced sounds of speech and music accompanied by needle scratch or extraneous background noises of various sorts. In phonography this ever present background noise was and still is a source of untoward disturbance and annoyance. It has been reduced somewhat by careful attention to the many processes involved in record production. For instance the wax on which the original recording is made has a homogeneity and uniformity undreamed of in the early days of the art. Electrolytic copper anodes, care- fully prepared solutions and accurate timing and temperature control now produce from the master record a copper plating of almost microscopic smoothness. The plastic compounds from which commercial records are pressed have been improved and re- fined to a remarkable degree. But in spite of all this we still have needle scratch or surface noise to con- tend with. With the advent of electrical re- cording the useful frequency range was greatly expanded. Electrical reproduction was capable of taking olf the record all that was on it in- cluding surface noise and then what did we do? We found by analysis and measurement that a great deal al- though not all of the disturbance from background noise lay in the frequency range above 5000 cycles. Electrical filters being easily con- structed we then proceeded to cut off by means of a low pass filter every- thing above about 4500 cycles. The surface noise disappeared to a con- siderable degree but so did most of the higher frequencies we had worked so long and diligently to include in our recordings. However, the ground noise was reduced and that was what we set out to do hence the experiment was a success. The use of film as a medium on which to record sounds involved all of the trouble heretofore encountered in disc recording and reproduction. As a matter of fact there is a strik- ing similarity between the processes. Instead of granular wax we now have to contend with emulsion grain; in- stead of graphiting, plating and pressing we have developing and printing; instead of a plastic shellac compound we have another piece of positive film stock as a final record; instead of defective phonograph nee- dles which do not fit the grooves we have light slits which get out of focus. You are no doubt all quite familiar with the reasons why ground noise interferes with reproduction and there is no necessity for a discussion of that particular point. If there were no ground noise or extraneous sound disturbances speech and music would be clearer — we will all admit that. The question is how can the ground noise be kept out or removed without interfering in any way with the wanted sounds or frequencies. * Supervising Engineer, RCA Photophon? West Coast Studios Eleven Mr. C. R. Hanna of the Westing- house Company and Mr. C. W. Hew- lett of the General Electric Company in the early part of 1929 did consid- erable thinking and research on this problem and at that time devised ways and means of accomplishing such an end. So far as we know Hanna’s method is the basis of all those used commercially today. Before we go further suppose we consider for just a few moments what ground noise is. A general definition would probably run something like this: “Ground noise is all sound evi- dent in reproduction which was not present in the original sounds.” You have all sat in theatres and heard this type of disturbance, but probably few of you have taken the trouble to try and analyze this background noise. It has been analyzed, however, and found to consist of disturbances from many different sources. For instance during a take on a stage or set it is almost a physical impossibility to have perfect quiet. There is always a certain amount of set noise due to movement on the part of the many people who are on the set at the time, the cracking of arc lamp housings or incandescent lamp housings, noise due to the cam- eras and their driving motors, to say nothing of a certain amount of noise which is caused by traffic outside the studio or extraneous disturbances in adjoining studios. The next source of noise is located in the microphones and their associat- ed amplifiers. No matter how care- fully an amplifier is constructed we always find a certain amount of noise due to circuit conditions and tube characteristics. If we add all of the components of noise mentioned above we find that up to the film we have a total noise level which may and often does assume considerable proportions. In some instances actual measurements indi- cate that this noise level is as high as 20 db. Since all of these disturb- ances are included in the signal fed to the recording mechanism, whether it be an Aeolight, light valve, or vi- brator, all of them make their impres- sion in the resulting sound track on the film. Every film on which record- ing is made has a certain definite re- solving power, that is, the ability to respond evenly to exposure. The emulsion on film which is susceptible to the action of light and develop- ment is a very sensitive medium. For this reason it is very desirable that it be treated with respect. It is not reasonable to suppose that we can subject a film to under expo- sure and over development or over exposure and under development and get uniformity throughout the result- ing opaque portions. In other words, unless the exposure and development is carried out with precision there is great possibility that the resulting granular structure will be a source of disturbance later on. During the developing, washing, and fixing of film there are plenty of opportunities, even in a well ordered laboratory, for the film to pick up small particles of dirt. By small I do not mean particles of a size visible to the naked eye. These particles may be, and usually are, microscopic in size. Their ability to produce noise, however, is still considerable. The handling of film, that is, of negative film and also of the positive stock, during the printing operation, is another potential source of noise. The developing and drying of the pos- itive print is still another source. You may well ask at this point how can the disturbance, due to a recorded sound track combine with dirt and make more disturbance. If you will consider for a moment the manner in which a sound track on film is repro- duced as sound the answer will be quite evident. Most reproduction from film is ac- complished by interposing the record- ed film between a source of light and T nue I've a photoelectric cell. The intensity and amount of light may be consid- ered as fixed, consequently any change in the opacity or width of the sound track as it passes through the light beam will cause a variation in the current through the photocell. The output of any given cell vanes directly with the amount of light change and is independent of the rate of light change. This being true it makes no difference whatever to a photocell whether the light is cut off or varied by means of a sound track variation or by specks of dirt or for- eign matter on the surface of the film. You will be shown later what a va- riable area sound track looks like and will note, too, why we are not par- ticularly interested in varying dens- ity. In normal variable area record- ing the sound track is always made up of equal portions of exposed and clear film. Any dirt or foreign matter getting- on the exposed or dark side of the track would have no effect whatever, but should it get on to the clear side its presence would be noticed as noise in the reproduction. The reason for this is evident. Dirt is opaque and the dark side of the track is nearly so, but dirt on the clear portion would cause a change in the amount of light falling on the photocell and pro- duce noise. At normal gain settings during re- production, the ease with which wanted sounds can be heard depends on the ratio of the recorded sounds to the ground noise level. In other words if the modulation during re- cording was low, i. e. : of the order of say 10 to 15% and we accumulated a little noise from each of the sources mentioned a few minutes ago we would find it difficult to distinguish speech or music above the noise level. The problem then was how to drop the level of ground noise to a point where it no longer interfered with recorded sounds. Hanna and Hewlett did it by making opaque all that por- tion of the track not actually occupied by modulation. An obvious and sim- ple solution wasn’t it? Their method was simple and ef- fective, too. They merely took a little of the output of the amplifier just be- fore it was fed into the recording mechanism, amplified it, rectified it and used the resulting direct current to furnish what may be termed a sec- ondary control over the vibrator. What happens is this : The output from an audio frequency amplifier is in the form of alternating current. The wave shape may or may not be symmetrical, but in all cases the current values during any cvcle start at zero, increase to a posi- tive maximum, decrease through zero to a negative minimum and then in- crease again to zero. If these values be plotted and a straight line be drawn through the zero points, this line may be considered as a base line above and below which the current values rise and fall. In RCA Photo- phone recording this base line corre- sponds to the center line of our sound track when the vibrator is at rest in its normal position. Since the vibrator is designed to change its position with respect to this base line under the application of current changes, its position at any instant is determined by the value of the current at that same instant. As the current rises to a positive maxi- mum, the vibrator twists to an ex- treme position in one direction. As the current falls through zero and de- creases to a negative minimum, so the vibrator twists back through nor- mal to an extreme position in the op- posite direction. Suppose now that some direct cur- rent were introduced into this circuit. It would have the effect of shifting the base line about which the vibra- tions took place to a new position and we would have a new zero line. Cur- rent changes and vibrator deflection with respect to the base line would remain the same as before but neither Thirteen would be the same with respect to if you will. In other words, it is nec- the new zero line. essary only to choose first the new It will be noted that the value of base line for the vibrator setting and the d. c. from the rectifier placed second the proper value of the d. c. to across the output of the amplifier is return the vibrator to its heretofore at all times proportional to the normal position in the center of the strength of the a. c. signal so we here sound track. Both are easily obtained have an automatic and positive con- and once set the ensuing action is trol over this d.c. component or “bias” simple, positive and automatic. Ground Noise Reduction R. C. A. Photophone System * hugh McDowell, jr. During the filming of the RKO pro- duction, “Hit the Deck,” in Septem- ber, 1929, musical effects were de- sired that would produce extremes in volume beyond the range of the nor- mal variable area recording system. At this time, Mr. Carl Dreher, Direc- tor of Sound at RKO Studios, men- tioned to the writer a system of re- cording devised by Mr. C. R. Hanna, of the Research Laboratory of the Westinghouse Electric & Manufactur- ing Company, for the purpose of elim- inating ground noise and consequent- ly permitting greater volume spread. The writer was much impressed by the principle that Mr. Hanna had made use of, namely, eliminating the unused clear portion of the sound track in the variable area method of recording, and proposed further in- vestigation. The objection was raised, however, that as this system dis- placed the position of the sound track at minimum modulation to the edge of the film, it was of doubtful utility in commercial projection machines, as any weave in the film in its travel might cause it to lose contact with the scanning beam during intervals of low modulation. The writer there- upon set about devising a system which would retain the advantages of Mr. Hanna’s, but would keep the sound track at all times in the center * RKO Radio Pictures of the seventy mils allotted to it on the film. The writer is also indebted to Mr. C. W. Hewlett, of the General Electric Company, for the use of a portion of his system which is similar to Mr. Hanna’s. Figure 1 Natural sound film recording must meet two essential requirements, namely, good quality of pickup, and range of sound from soft to lound with only a tolerable amount of noise. In standard methods of recording, the former is accomplished, while the lat- ter is restricted to the limiting factor of ground noise caused by the unused clear portion of the emulsion on the film, admitting unnecessary light to the photoelectric cell of the reproduc- ing equipment. As the light reach- ing the photocell is in effect the car- rier of all current within the cell, it Fourteen is evident that unused clear portions of the film cause the cell to produce energy not required by the legitimate sound, thereby producing extraneous noise in the output. Noise is also produced by the transparent portion of the film not being totally clear, but containing dirt, scratches, etc., which disturb the carrier in such manner as to cause additional noise, in effect, reproducing the dirt, scratches, etc. It is obvious, therefore, that in the standard method of recording, sound volume reaching the film must at all times be adequate to overcome the ground noise factor, which remains constant. This requirement restricts the compass of electrically reproduced music and is an obstacle to natural and effective reproduction. The remedy for this condition in variable area recording is found in eliminating the clear portion of the film, except at times when the modu- lation requires it. With this accom- plished, it is possible to allow the modulation to fall to its natural mini- mum and rise to its natural maxi- mum, for with the clear portion of the film eliminated, ground noise no longer remains a constant quantity, but changes in proportion to the de- gree of volume. Roughly, in standard methods of recording, the volume range from minimum to maximum is approxi- mately 20 db., while with the anti- ground noise methods of recording described herein, the volume range may be extended to approximately 35 db. Electrical and Mechanical Design The following description of the device illustrated in Fig. 1 does not take into account later simplifications in design. Connected to the output of the re- cording amplifier is a two-stage am- plifier of sufficient power to operate a rectifier tube following. The d. c. output from the rectifier is then passed on to a direct current ampli- fier which amplifies the d. c. impulses of the rectifier, increasing their am- plitude to any desired point, by vary- ing the input voltage on the two-stage amplifier. The d. c. impulses are then fed through one-half of a voice coil of an electro-dynamic shutter move- ment to a resistance and battery of low voltage which aids the flow of current from the plate circuit of the d. c. amplifier to ground. Across the aiding battery and ground is con- nected the remaining one-half of the voice coil which is excited by the aid- ing battery when the normal plate current is depressed, due to rectified modulation. It is seen, therefore, that two voice coils in series in this manner are ex- cited in such a way as to cause one coil to exert pressure, when excited, in one direction, while the other coil exerts an opposite pressure when ex- cited in the other direction. This bal- anced circuit of voice coils in the mag- netic field causes pressure to be ex- erted equally and oppositely in both directions, and in opposite phase. To these voice coils is directly attached a moving shutter actuated by the voice coils which is placed mechani- cally in the beam of light reflected by the vibrating element of the re- cording system. The shutter, there- fore, moves in proportion to the amount of input to the two-stage am- plifier, moving outward under pres- sure of the rectifier and voice coil to accommodate the peaks of the modu- lation on the film, and moving back- ward when the modulation decreases, also under pressure of the voice coil. It is obvious, then, that electromag- netic pressure is exerted in both di- rections in the functioning of the shutter. The electromagnetic assembly is supported mechanically by a lathe carriage arrangement so that manual adjustments may be made to place the shutter in the proper position with respect to the light beam. The vibration of the shutter is in exact accordance with the d. c. im- pulses of the rectifier, and, therefore, it admits light to the extent required by the peak modulation reaching the film at any given instant. When no F ij t e en modulation occurs, the shutter is ad- justed to admit to the film, light ap- proximately five thousandths in width as against thirty-five thousandths width for the normal variable area recording system. It is seen by this that there remains about 10 per cent of the clear portion of the film that formerly existed. This factor in turn admits only about 10 per cent of the light formerly reaching the photo- electric cell in the projector, cutting- down overall excitation of the photo- cell when no sound is in evidence, and consequently reducing extrane- ous disturbances in the cell. The equipment used in recording during 1930 consisted of a two-stage amplifier-rectifier and direct current amplifier built in a steel box 18x18x8, internally divided, the partition sep- arating the d. c. amplifier from the other units. The two-stage amplifier is operated from a small B-supply working from 50-cycle alternating current and supplying 250 volts to these stages. The direct current am- plifier consisted of seven UX-250 tubes in parallel, fed by a 180-volt storage battery. A small meter con- trol box containing two 0-to-500 mil- liammeters is used with a switch for breaking plate current and aiding battery current to the voice coils. Each voice has connected in series with it a milliammeter indicating the variations of current in each circuit. A variable resistance is also used in series with the battery to adjust its value so as to make the voice coils balance electrically, that is to say, when one is at maximum current, the other is at zero, and vice-versa. These meters, therefore, represent the movement of the shutter. Summary Work on the system described was first started in November, 1929. Prac- tical results were obtained in Feb- ruary, 1930, and the device put into production on Radio Pictures’ “Dix- iana,” in March, 1930. “Dixiana” was released in August, 1930. After further development, the system was again used on Radio Pictures’ pro- duction “Half Shot at Sunrise,” re- leased in September, 1930. Since this time, development has continued with the aim of simplifying and re- ducing the amount of apparatus nec- essary and to procure simpler adjust- ments in operation. The device will continue in use on forthcoming RKO productions. Ground Noise Reduction R. C. A. Photophone System * L. E. CLARK The recording edge in a variable area system is normally adjusted to the center of the track. If for any reason it becomes shifted, it can be returned to its correct position by either manual movement or by the application of a small direct current of the proper magnitude and direc- tion to the vibrator strings. In the Hanna device, the edge is set normally to a position close to one edge of the sound track and a device arranged so that direct current is passed through the galvanometer strings in such a direction as to force * Sound Director, Pathe Studios. Sixteen Due to the many photographs embodied in Mr. L. E. Clark’s pa- per a large section of it has been omitted. We believe, however, that the subject will be well understood from the accompanying articles. — Editor. the edge toward the center of the track and in such amounts that the edge is back to its normal position when a 100 per cent modulated signal is applied to the system. (Continued on Page 36) San Francisco Chapter No. 16 Entertains Visitors By FRANK W. COSTELLO, A. P. S. Chapter No. 16 was pleasantly sur- prised to learn last Tuesday morning that Bros. Wallace G. Crowley and Harold E. Alford had arrived in town. Their unexpected arrival pre- vented us from planning a sumptu- ous form of entertainment befitting two industrious young fellows, but with the cooperation of our Presi- dent, Frank Seavier, and Paul Gaff- ney, of the Board of Governors, the boys were introduced to some of the interesting sections of our city, in- cluding Chinatown and North Beach. Somewhere in their travels, they en- countered Danny Knowlton, District Superintendent of E. R. P. I., and George Lancaster, Division Represen- tative of the Advisory Council. From there on. Brother Seavier escorted the boys through some of the secluded haunts of San Francisco. They re- turned to headquarters in time to at- tend our regular Tuesday evening Chapter meeting, and might say here, that although the meeting was sort of impromptu and scented with mirth, it was one of the most important and interesting of the year. Brother Seavier was feeling twenty years younger that night and conducted the meeting more as a master of cere- monies would. The first speaker on the program was Brother Lancaster, who ex- plained in detail the standard release prints — their advantages, minor in- accuracies and the future possibili- ties. George likes to bring a little comedy into his talks, and he kept us entertained all through his speech. Danny Knowlton next gave us an in- teresting talk on the new E. R. P. I. screen. Quite a jump from an ampli- fier tube, but Danny can lecture on anything pertaining to a theatre. Brother McGown of A. P. S. No. 7, now with the Department of Elec- tricity, outlined briefly to us the work he is engaged in at the present time, namely, equipping police automobiles with radio. Brothers Crowley and Alford then gave us a clear and con- cise explanation of the aims and pol- icies of The Loudspeaker, and the work they are doing towards bring- ing before our fellow projectionists, information of a technical and prac- tical nature, which is in direct line with our work. Being located in the geographical center of the motion picture industry, surrounded by scores of technicians, laboratories, studios and research engineers, they are in a position to secure this infor- mation more readily than a staff of representatives in a far off city not in close proximity to the heart of the in- dustry. San Francisco Chapter No. 16 vot- ed unanimously to subscribe to The Loudspeaker, realizing that it is the true mouthpiece and representative of the Western Projectionists. Our Chapter feels highly honored by the visit of Brothers Wallace G. Crowley and Harold E. Alford, and we extend to them, and all members of No. 7, A. P. S., a cordial invitation to visit us whenever convenient. San Francisco Chapter No. 16, American Projection Society, had the extreme pleasure last evening of meeting two well known celebrities — Dr. McKenzie and R. H. Hart, who gave us a very interesting, as well as instructive lecture. Dr. McKenzie is a pioneer in research work involving sound engineering. In 1914, he re- ceived his degree of Doctor of Phil- Seventeen NOVEL DATE STRIP IDEA From BELL, CALIFORNIA Several months ago the projection- ists at the Alcazar Theatre, Bell, Calif., Clyde McGinnis and Clyde Salyer, decided that the date strips attached to coming attraction trail- ers were an eyesore. To remedy this they made their own, copying the background title card after the Fox Movietone News blazing sun. Each title having an in and out fade and set over for sound on film. This not only matched the trailer to which it was attached, but prevented motor- boating when the fader was acciden- tally left up a second too long by rea- son of the fact that the sound track was solid black. The success of this system sug- gested a further step, that of dubbing sound on the house titles. They watched their chance and when a sound on film variable area subject came in they had just the right music to fit their titles . They rushed it to a laboratory and had it dubbed into their original negative. Prints made from this negative have fitting sound scores . This bit of cleverness on the part of these progressive projection- ists have saved the Alcazar audiences from a bad dead spot in their show. This is a step in the right direction. It is hoped that many other projec- tionists will follow their lead. osophy. In 1922, he accomplished creditable results in producing sound on film, and has continued from then on in scientific research work, and at the present time is consulting engi- neer for E. R. P. I. Mr. R. H. Hart, Superintendent of Personnel for Western Division, has long recognized the valiant efforts of A. P. S. Chapters throughout the country, and particularly in the West, to improve their knowledge of sound recording and reproducing, and he has been instrumental in procuring for us lecturers well versed in sound and electrical engineering, who have imparted to us, first hand informa- tion that has been a great help, and which could not have been accessible from books or literature on the mar- ket at the present time. When Mr. Hart took the platform and said : ‘Boys, it is indeed a pleas- ure for us to be with you,” we could plainly see that he was sincere in his remarks and assured us that all avail- able information and future data on subjects of vital interest, will be forthcoming to us. Dr. McKenzie elaborated extensively on modern methods of producing sound on film, Eighteen and the characteristics of amplifiers in reproducing the finished product, and his explanation covered all details which were of great benefit to us. Dr. McKenzie and Mr. Hart mention- ed also that inasmuch as Chapter No. 16 is aggressive and takes such a whole-hearted interest in all technic- al information and explanatory work- ings, coincidental with our profes- sion, it will be a pleasure and a de- light to furnish us with the necessary data and technical advisers, that we may receive first hand information on all new developments in our indus- try. Chapter No. 16 wishes to extend to Dr. McKenzie and Mr. Hart our sin- cere thanks and appreciation for the services they have rendered us. Editor’s Note: American Projec- tion Society has received the recogni- tion of the foremost engineers in sound recording and reproducing. To all those who do not belong to the A.P. S. and who are eligible to join — why not avail yourself of this opportunity to be a participant of information which is the aggregate accumulation of world renowned research engi- neers? Th ree Position Screen Unit Developed by Weaver Bros. The modern trend of motion pic- ture presentation is to change the size of the screen to what has been named magnascope proportions. At other times the same screen is used for wide film or grandeur proportions. This is done by moving the top masking piece and the side masking pieces to allow a greater expanse of screen surface to be revealed. The actual moving of these masking pieces pre- sent a very complicated problem since it must be done quickly, silently and accurately. Realizing all of these facts, the Weaver Bros. Manufactur- ing Co. of Los Angeles conducted a series of experiments in view of building a motor driven apparatus which would fill all of these require- ments and could be remotely con- trolled from the projection room or the stage switch board. The outcome of these experiments is the Weaver Bros. 3-Position Screen Unit, which is announced elsewhere in this issue. This unit is a marvel of accuracy. It can be set to stop the masks at any predetermined location. It is very easily operated by only four switches, one for each of the three sizes and one for stopping the apparatus in case an error is made in pressing the wrong switch. Several unique features are incor- porated in the apparatus. A pilot light is used for each position which indi- cates the position of the masks at all times. This reduces the possibility of error to a minimum. The entire ap- paratus is very compact and is housed in a metal box which can be mounted on the screen frame. The motors are suspended on material that will not transmit the vibrations of the mo- tors to the frame of the screen. This is a big feature since it renders the unit practically silent in operation. In the event that the ropes become en- tangled and the motor stalled no harm is done because the designers have provided for this contingency in two ways. First, a heat relay is in the motor circuits w7hich prevents damage to the motors. Second, the unit can be disengaged with a clutch mechanism which makes it possible to operate the masks manually. One of the outstanding features of the unit is its flexibility. Regardless of the position it is in the projection- ist can go directly to any other posi- tion by merely pressing the button for the next size desired. Another very desirable feature is that there are absolutely no working parts in the open. This reduces foul- ing to a minimum. Several installations have already been made and they have proven en- tirely satisfactory in every way. These units are a distinct advance- ment over the old types of mask con- trols. It is freely predicted by those who have had the pleasure of seeing this unit in operation that it will w7in instant endorsement wherever shown. i i i IT MUST BE TRUE » » » Bro. John O’Connell, Secretary of the San Francisco Labor Council, tells about a man seen walking down the center of Market Street shouting, “No, No,” repeatedly. An officer stopped him and asked what w^as the idea. The man paused long enough to say, “I’m a Hollywood yes-man on a vacation.” Nineteen Celestial Control By J.B.G. The scene opens where our mortal scenes close: The Gate. A lone fig- ure stands there. He is panting, per- spiring freely and biting on some- thing. That something is his tongue ; for he is nervous as Saint Peter parts the emerald portiere and steps for- ward. To think that he, Brother William Rose, has really done so! To think that he would die to see the day when he would greet Saint Peter! It was unbelievable. It truly was! But here he is; and here is Saint Peter. And between them nothing but the ether be i n g pierced by their nervous ap- praisals of each other. For (you’ll have to learn sooner or later, anyway) Saint Peter is also ner- vous. To think that he would be- ll o 1 d the day when this projectionist mortal would come under his ken ! It was unbeliev- able. It truly was! “Just a minute,” called Saint Peter, “I’ve a hunch from Notre Dame that you’re in the wrong isle.” William paused, counted ten, and then decided to test the splice. “Nope!” he boomed, glaring defiantly at Saint Peter. “I’m in the right aisle and the right joint! The usher- ette with the lace cuffs and heavy mascara directed me here — and here I stay !” “Well, Bill,” stalled Saint Peter, (for he’s a pretty good door-man), “You don’t look so hot to me and I’m not at all sure you belong up here, but business is bad and I’ll take a chance.” “Thanks,” said Bill, showing his in- tense relief by kicking out a ten thou- sand dollar chunk of gold from the steps and heaving it at the platinum screen. “Who’s the chief? Any smoking? Do the usherettes bring up the schedules?” At these pertinent questions Saint Peter smiled broadly, spread his arms out and bent forward in a low bow. “There are no chiefs — no schedules ; this is Heaven.” “W-what?” gasped Bill, as though finding the overtime on his check without an argument, “Run that slide again.” “This is Heav- e n , ’ ’ reiterated Saint Peter gra- ciously. “Pick up your crescent wrench and screwdriver and find yourself a suitable palace. Be gone.” And so Bill, mightily grateful and this being in Heaven! How asi- nine, how incongruous, now, were the directions his mortal friends had giv- en him in suggesting where he could go! He felt buoyant, youthful, im- bued with the same inexhaustible vi- tality he had when sound first came in and when he carried the fader at point fifteen to assure the horns o’ plenty. Nothing to worry about now. But was there? And then poor Bill began to worry. Was this but a preview of his qual- ifications? Would he make some mis- step or misframe only to find him- self hurtling downward, downward, to shovel the proverbial coal instead of the proverbial snow? He recalled that initial scrutiny Saint Peter had seared him with. And trembled. He had felt that before, on earth, when he entered a strange theatre to do re- We can’t vouch for the authen- ticity of this narrative, but it is so touching, so entirely logical, so delicately and yet so thorough- ly tinted with the altruistic color of the Hereafter that we give it credence, and with that credence — publicity. Twenty Projectionists, Attention! TT HE Standard Release Print which has come to play such an important part in our profession has been in operation for a suffi- cient length of time to allow all projectionists to become fully acquainted with its operation. Its mechanical and theoretical practicability has been thor- oughly tested in thousands of projection rooms throughout the country. Many ideas have been evolved by the projectionists that would be invaluable to the Academy of Motion Picture Arts and Sciences in their attempt to develop the standard into a perfect working system. It has been decided therefore to distribute a questionnaire to projectionists throughout the country which will seek to determine the representative opinions of the men in the field concerning pos- sible improvements for the standard. The American Projection Society . . . . . . has arraigned itself solidly behind this movement, realizing that by this method the Standard can be made into the ideal and will represent the best available tech- nical information. This information can only come from you pro- jectionists in the field. On the reverse side of this insert is a questionnaire which should be filled out and returned to the Editor of The Loudspeaker at once. Address 1264 Welton Way, Inglewood, California. Your suggestion may be the answer that will definitely solve this question of change-over cues in a manner suitable to all con- cerned. Fill out the form on the next page and mail it in now. Justify the confidence of the industry in the projectionists by responding TODAY. SURVEY ON HOW TO IMPROVE THE RELEASE PRINT STANDARD X X X G £ -jf >; 3 O ^ x S ° 1=5 73 £ a; o G c/2 £ O r- 02 CO ^ O 2 g u X* OS X Ph HH 44 x a; ° § £ ^ s < >> o 0) 3, 0) > CO X Sh h-> 3 CO 03 ,rH Hr1 3 O g o £ G (D CL «* o o_, a> ' o S 8 ■g £ as 3 « X a Ph h * "E § 3 > w to X 3 c n X 3 02 H H-H C/2 02 £ as ^02 X *S H-> a? O -Q >>*< to 4? x £ G .2 o o G 'O 44 .2 2° -5 <1 o o> o' a as h-> 3 as X hh> hh> 3 X £ G O be 3 ■3 G 0) ST X x” as be as X o c 73 as o o «w G as a> x £ x 3 X r-1 3 co 0) x E-i a 3 £ as o O X o 44 x ^ M H-> x as -h ° ^ a co bo *H 3 O as co h-1 *X-G X as as . Sh 33 >» as -r G 5J3 S 2 o -c «-|S ® cS ^ O >s CO X £ 2 3 -G c/2 G 0) Tg G eg eg « £ - Sh £ o On X A a tl OS G 3 co X .£? 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Send it in NOW . Address: 1264 WELTON WAY, INGLEWOOD, CALIF. Latest Academy Publication “Recording Sound for Motion Pictures” available to Projectionists . . . pphile a few projectiotiists have opportunity to go through the Hollywood stu- dios, the Western chapters have frequently had the advantages of speakers able to re- view the technical production end of pictures from first hand experience. The educational program of the Society has never been limited to just the equipment of the projection room because a good projectionist running a sound show conies in contact with the work of all the technical crafts all down the line back to the studio. The new book, “Recording Sound for Motion Pictures,” which is being published by the Academy of Motion Picture Arts and Sciences, provides in complete form all of the information on the subject that a projectionist requires. While it has several good chap- ters on sound projection it was written by the leading sound engineers of the big studios as an extension of a school for studio employees that was conducted by the Academy. It deals in a thorough way with such subjects as Practical Technic of Recording in the Studio and on Location; Booms, Blimps and Microphones; Different Systems the Studios Use — Vitaphone, RCA Photophone, Fox Movietone, Western Electric Light Valve; Acoustics of Sound Stage and Theatre; the Film Laboratories and Their Work; Assembling the Talking Picture and Technical Terms for the Motion Picture Technician. There are also chapters on sound reproduction by S. K. Wolf, John O. Aalberg, F. L. Hoppera and R. H. McCullough. The book contains 400 pages with over 200 diagrams, charts and photographs of studio operations. One of the provisions made by the Academy was that before the book should be available to other readers, first consideration should be given those within the industry. Members of the American Projection Society and other progressive projectionists can take advantage of a special pre- publication offer to get the book ior a dollar less by ordering before May 1. The pre-publication offer is a price of $4. After the book is published on May 1 the retail price will be $5. In order to take this opportunity, fill in the coupon herewith and send it with your check or currency for $4 to the EDITOR of THE LOUD- SPEAKER. O . a; & Ss a- Co * H SJ lief. He must pull himself together! He would be cautious. He would ex- ercise every care to lose no loons. He would prove to the old gent that he appreciated his admittance here. He would. Yes, he would ! And when our Bill said he would, he would! Suddenly looming up before him was a girl, a delicately proportioned girl with wide, innocent eyes and luscious red lips which were parted and smiling. Bill missed a fader step, then took three to make up for lost time. But just as he reached the lass he recalled his resolution. Stop- ping with a jerk that would loosen any flywheel, he forced himself to an- swer the question : ‘Can I afford to speak to this gor- geous mass of pink flesh and feath- ers? Will I, by so doing, arouse the disapproval of Saint Peter, who in recourse may send me back to Earth?” And our Bill answered : “No. I cannot, will not, take the chance!” And so deciding, he turned away from the lass, who indeed was now wondering what was the trouble with this egg, and retraced his steps to Saint Peter. “Pete,” said he, bringing his prob- lem into focus at once, “There’s a neat chunk of femininity over in yon- der diamond field. What’s the worst I can get if I speak to her — you know — knock myself down to her — that is — er — ” “My boy,” replied Saint Peter beatifically, “Didn’t I tell you this was Heaven? Make friends of whom you choose.” “You mean the sky’s the limit?” gasped the incredulous Bill. “There is no sky,” smiled Saint Peter, very coyly for a man his age. “And Paramount-Publix, Fox-West Coast, or R. K. 0. haven’t even a toe- hold. This, you dumb-bell, is Heav- en.” And so Bill ran back — fairly flew back — over the celestial road. And she was still there, this blonde lass of the delicate proportions and the lus- cious red lips which were parted and smiling. And the smiling lips, as Bill skidded to a halt, smiled even more — and their lusciousness seemed even more luscious ! — and her blonde, silk- en hair, even more blond and silken! “Hello, biggie boy,” came tingling from her lips, as though surely a four-manual Wurlitzer nestled with- in her breast to lend the sweetness to her voice. “Heh — heh — hello,” stuttered Bill, standing there wavering, and pant- ing, and sighing, and feeling for all the world as though he had run the news with the outside horns off, so glorious did she seem — this creature of creatures — this superlative dream of dreams. “I — I was wondering if maybe I could speak to you,” he mum- bled at last, his audio stages at low, low ebb. And she smiled again, this girl, and made a deft, light movement as she jumped to feet which appeared like little mice, so small were they and so fast did they carry her to him. And there this cute little trick stood, right in front of our Bill, her fragrance bewildering him, her near- ness causing his strained heart to motorboat. She raised her soft arms, her dainty hands reaching for the lapels of his coat, her fingers fondling his A. P. S. button, then creeping upward to his manly, speciously- shaved chin. “Merciful grid-leaks!” yelped Bill, “I can’t stand this! I want to know your name. I — I — ” But the lass only snuggled closer as she asked : “Why do biggie boy want to know my name?” “So’s I can tell you mine,” an- swered Bill, “ . . . and then we can figure we’ve been introduced and — and — ” “And what?” was the lass’s tin- kling query. “An’ — an’ — and then we can shake hands,” finished our embarrassed Bill. “Silly biggie boy,” reproached the lass. “In Heaven we don’t shake (Continued on Next Page) Twenty - one Projection Advisory Council Luncheon in New York PROJECTION PROBLEMS ARE DISCUSSED .. » .» Fixing of standards for release prints was the biggest problem solved in 1930 from the standpoint of pro- jection, declared President Thad Bar- rows of the Projection Advisory Council at a luncheon last month at the Astor. Mike Levee, executive manager of the Paramount West Coast studio, spoke on noiseless recording and other subjects. He pointed out that the new valve, which permits an in- creased range in recording range, al- lows the continual running of a pic- ture at one fader level. This elim- inates regulation on the part of op- erators in the booth who, owing to the various machine noises about them, are not in a position to effect- ively control the sound volume in the auditorium, he said. William F. Canavan, president of the I.A.T.S.E. and M.P.M.O., assert- ed that much booth equipment is out of repair owing to depressed business conditions which caused exhibitors to postpone this cost. Few interruptions occur nowadays in the projection of sound film programs owing to the competency of operators, he said. He described current pictures as “fine.” Keeping reproducer equipment clean is the best preventative against breakdowns, said H. M. Wilcox of Erpi. He stated that the greatlv re- duced number of emergency calls to his company indicates that projec- tionists have become intimately fa- miliar with equipment. Lester B. Isaacs of Loew’s said he failed to see any particular im- provement in booth equipment but believed that the operators them- selves have improved in their work. Others who spoke briefly were: J. P. Lilley of Harrisburg, connected with the Department of Labor; P. A. McGuire, Harry Rubin, Sam Kaplan and N. D. Golden. Attendance at the luncheon represented various cities outside of the metropolitan area, and included a good-sized dele- Tnv e n ty -t 4 [ Ether being highly volatile, dries quick, hence can only get a • ■ surface grip on the film and soon opens ! ; ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT having ; low volatility evaporates slower BUT melts and fuses the broken . film into a WHOLE. • A Film Splice made with 2 in 1 will S1ICK IMMEDIATELY • ’ but WILL NOT stand an immediate PULLING TEST. . MAKE YOUR SPLICE— REEL YOUR FILM IN CONFIDENCE— AND FORGET IT! It’s $1.25 a Pint Parcel Post Also Makers of Truevision Parts, Fire X Liquid, Lens Paste, Rust Remover, , Gum Remover, Perfumes, Etc. ! [ 2 CEMENTS INCORPORATED INTO 1 FOR USE ON SAFETY AND ; ; REGULAR FILMS ! . . H ewes-Gotham Co. . 520 W. 47th St. New York •s a- * Thirty-eight 0. ► ► ........... ."i »» V.~. ........ Western Projectionists ! All progressive projectionists, technicians, service men and engineers should be subscribers and readers of “PROJECTION ENGINEERING” The largest technical circulation of any motion picture publication TELL YOUR FELLOW CRAFTSMAN ABOUT THE GROUP SUBSCRIPTION RATE The subscription rate for individual subscribers is $2.00 a year or $3.00 for two years. The group rate of $1.00 is available to you when 4 or more subscriptions are sent in at one time. < For Your Convenience < — — — — — — — — — — — — — ■ ■— — — BRYAN DAVIS PUBLISHING CO., Inc. 52 Vanderbilt Ave., New York City. Enter the following subscriptions to Projection Engineering at the $1.00 a ] year Group Rate. Name « Address < Town State - * Classification < Name Address Town State * Classification Name Address Town State..... * Classification Name Address Town State * Classification Name _ Address Town State * Classification , *PIease classify subscriptions sent in as follows: M — Manufacturer E — Engineer P — Projectionist Including execu- tives, purchasing agents, plant su- T — Technician D — Dealer or Service perintend ent, Man foreman, etc. BRYAN-DAVIS PUBLISHING CO. 52 Vanderbilt Avenue, i i New York City LS-3 — — — -a Thirty - nine A THE ASHCRAFT Air Bl asfc Projection Lamp Designed to supply adequate light for present day large screens at minimum expense THE ASHCRAFT AUTOMATIC ARC CO. 4214 Santa Monica Boulevard ALLOY EMBLEMS FOR YOUR CAR APS Emblem, 2%" in diameter, beauti- fully enameled in black and silver,, with attachment for fastening to your radiator. Price $1.00. IATSE Emblem 4" in diameter in blue and silver enamel with attachment for fasten- ing to your radiator. Price $1.00. iii This emblem can be furnished with any number for $1.50 CLYDE W. SHUEY, 51 Rose Avenue, Venice, Calif. Manufacturer and Distributor Q o rty SERVICE that keeps the show going A »♦* >♦* A A A A »♦* >♦* »♦* A A A »♦* A A A A A »♦<* A A A A A A A A A A A AA A AA AA »**AAA A.*«*.AA AAA A A A v v v >♦* y v v yy ♦* yv v vvvvv y vyyy yvyy y yyyy vyyyyyy%~**y vvyv vv w w v 77/Tr /5 jet/tf you ietny tad that is what WE ARE READY TO GIVE NIGHT AND DAY Better Yet See that your machines are always in the best mechan- ical condition. Do not wait until the last minute. Let us look your machines over and give you an estimate on any needed repairs. We maintain a complete repair department and stand behind every repair job. Parts and labor fully guaranteed. CALL US FOR ANY EMERGENCY Day Phones REpublic 3151 REpublic 3152 Night Phone CHicago 3649 BRECK PHOTOPLAY SUPPLY CO. 1909 So. Vermont Ave. Los Angeles Read what a user of Cue-Meters has to say . . . 1 1pl.LY^V,Ojl>l).fC'AI.-lh. Janaary 22, 1931 Theatre Engineering Servloe Co,, 1442 Beaohwood Drive, Hollywood, California Gentlemen: I wish to offer my slnoere appreciation to year oompeny for the great work you did In developing the Cue-Ueter. Every theatre in oar territory is now equipped with Cue-Meters, and einoe their Installation we have had no trouble with ohange-overs, and our curtain oues are made perfectly. This of oourse, enables us to run a perfect continuity show, as there is never a word of dialogue lost. We are able to change over with- in three frames of the desired point of change on the incoming machine and there Is never any exouse for not playing right up to the last note of rausio. Also the film Is sent back to the Exchange in the same condition as when received by them. This is a great help, as in most oases we own the film. Without the use of Cue-Meters, it was absolutely essential that the film be narked in some way, and every theatre had to put on a different mark. By the time a reel had been run in eight or ten theatres, the last hundred feet was marked up something terrible. Slnoe the use of Cue-Meters the film is reoelved by the Sxohange in the same condition as wen originally sent out to the first-run house. The installation of Cue-Meters in all the theatres would effeot a tremendous saving in prints and would pay for themselves many time3. Keep up the good work. Boys. Yours sincerely. Supervisor of Projection, E0:P3 Warner Bros. Theatres, Ino. CUE-METERS ARE INDISPENSIBLE THEATRE ENGINEERING SERVICE 1442 Beachwood Drive COMPANY Hollywood, California DON’T G U € S S USE CUE-METERS LOUDSPEAKER \AJ C C *T TT k W I cKN % s J J May, 1931 Twenty- five Cents • Logical Reasons Why National Should Service Your Theatre: NE source of supply — a definite standard of quality, and that the very best. Everything you need for the mechanical oper- ation of your theatre can he supplied, promptly and with utmost satisfaction through National Service. A nearby source of supply at 30 well-equipped, well-stocked branch stores, with sales and service men always available on short notice, experts TRAINED TO SERVE YOU CONSCIENTIOUSLY, regardless of what your requirements may be. THE PROJECTION ROOM requires careful consideration in any theatre. Sound film projection makes necessary the pro- vision of precision equipment and careful maintenance. National Service features every need for the modern projection room and National Service Men are on the job day or night to keep the show in operation. Many new and modern improvements for better projection are now available at your nearest National Branch store and a demonstration incurs no obligation. “If it is needed in the projection booth National has it.” National Theatre Supply Co. Executive Offices--92-94-96 Gold Street, New York SIMPLEX ACCESSORIES FOR SIMPLEX PROJECTORS GIVE MOST SATISFACTORY RESULTS Lens Aligning Device gitfigfe r TAe/nternationa/ fi-ojector Lens Focusing Assembly Send for Booklets Giving Full Particulars INTERNATIONAL PROJECTOR CORPORATION 90 GOLD STREET NEW YORK One EARNING THE CONFIG WEAVER BROS 3 POSITION SCREEN UNI‘ SELECTIVITY . . Can be changed from any setting to another setting instantly. FLEXIBILITY . . Pilot lights signify what position screen is in at all times. COMPACTNESS . . Unit easily mounted on screen frame. SAFETY . . . Heat Telays protect the motors from damage. REMOTE CONTROL . . Can be operated from any number of stations desired. ACCURACY . . . Stops tbe masks in tbe exact predetermined position. QUIET OPERATION . . Motors cannot transmit vibration to the screen frame. EXCLUSIVELY DISTRIBUTED BY ARMSTRONG STUDIOS 1717 Cordova Street Los Angeles, California Two INC E OF AN INDUSTRY Work lamp switch Stop switch Standard screen control switch Work la. Top mask limit adjustments Top mask moto. Standard . selector relay Heat relay Top mask motor Magnascope selector reiav uses - Top task motor Outside wiring terminal strip Fuses - Side mask motor Reversing switches Side mask motor Heat relay Side mask motoi safety switch Model S.MW 3 Position Screen Unit [ Electrical interlock Reversing switches y_y: KB - I Top mask motor jf', SB' •'wp1 J Magnascope screen ^Lv>, Wide screen B ■ control switch control switch P »nask limit 1 T adjustments Pilot light switches ^5 hr e e »,♦ ♦ ♦♦ ♦ ► ♦♦♦♦♦ VVv V V V ♦ ♦♦ ♦ * * * Projection Equipment AND Maintenance Co. Quality, Workmanship and Service ALL REBUILT WORK FULLY GUARANTEED NO CHARGE FOR SERVICE MECHANISM DURING REPAIRS (3^ Phone or Write L. M. (Louie) WUTKE 3608 Farris Drive C. M. (Chuck) FOWLER Culver City, Calif. WHitney 4652 — Phones — or Culver City 3869 fyo u r s :**1**1**1* A Technical and Educational Publication. Devoted to the Western Projectionist and his Progressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G. CROWLEY H. E- ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE l2&4 Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Plea*ant7332 Circulation JAMES B. GILLARD, Oakland Editor FRANK W. COSTELLO, San Francisco Editor 1436 Delaware St. Berkeley, Calif. 1230 Hyde Street, San Francisco Technical Editors! A. C. SCHROEDER, D. B. McGOWN and R. H. McCULLOUGH Volume II. MAY , 1931 Number 5 CONTENTS S. M. P. E. Aims and Purposes By Emery Huse . . 7 The Ortho-Krome Screen By T. L. Doivey .... 9 Visual Education in San Francisco By Frank W. Costello 10 Photo Electric Cells By Richard, Van Slyker ... 11 Oakland Doings By J. B. G 15 Standard Discussion By Geo. J. Lancaster, P. A. C. . 16 The Eighth Art By Dr. Clinton Wunder 18 Just How Clever Are You By R. E. Clark, A. P. S. . 20 Craft Technical Data By A. C. Schroeder, A. P. S. . 21 Things in General By the Editor 24 Pin Spots 25 Chapter Doings — California Chapter No. 7 and San Bernardino Chapter No. 19 26 Secretarial Comment — California Chapter No. 7 . 27 Elementary Sound Physics By Robert D. Timmons, A. P. S 30 Published Monthly, Sponsored by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Blvd., Los Angeles, California T-r-ig EDDIE HARRIS Asks — "Are YOU Interested In A WELDED Film Splice — or — Does JUST A PATCH Satisfy You?” Our Slogan: "The Splice is Stronger Than the Film Itself,” is not merely a "catch-word” — It means that the break in the film is ACTUALLY welded as steel is welded — FOR PERMANENCY! We feel, at this time, that an analysis of the working of ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT and the ! ordinary QUICK DRYING cements on the market, will clear up ! I a mis-understanding as to the value of a quick drying cement and one of less volatility. 1 ! To WELD a break you must FUSE and MELT the broken pieces ■ ; into each other to become ONE. To PATCH a break you just • use an adhesive to make TWO SURFACES stick to each other 1 [ FOR THE TIME BEING — They will come apart — in the case of film, ether will do that. 1 [ Ether being highly volatile, dries quick, hence can only get a ; surface grip on the film and soon opens ! ! : ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT having ; ; low volatility evaporates slower BUT melts and fuses the broken . film into a WHOLE. ] ■ A Film Splice made with 2 in 1 will STICK IMMEDIATELY . but WILL NOT stand an immediate PULLING TEST. 1 MAKE YOUR SPLICE— REEL YOUR FILM IN ; CONFIDENCE— AND FORGET IT! It’s $1.25 a Pint Parcel Post Also Makers of Truevision Parts, Fire X Liquid, Lens Paste, Rust Remover, 1 Gum Remover, Perfumes, Etc. ] : 2 CEMENTS INCORPORATED INTO 1 FOR USE ON SAFETY AND ] ; REGULAR FILMS ! H ewes-Gotham Co. 520 W. 47th St. New York I :| Six Society of Motion Picture Engineers AIMS AND PURPOSES By EMERY HUSE EMERY HUSE, Secretary, S. M. P. E. Pacific Coast Section The Society of Motion Picture En- gineers was founded in 1916 by a group of technical men in the motion picture and allied fields. Its purpose is best expressed in its constitution by the following statement: “Ad- vancement in the theory and practice of motion picture engineering and the allied arts and sciences, the stand- ardization of the mechanisms and practices employed therein, and the maintenance of a high professional standard among its members.” The Society is composed of the best technical experts in the various re- search laboratories and engineering branches of the industry in the country, as well as executives, techni- cians, cameramen and projectionists in the manufacturing and producing ends of the business. The Society has within its organi- zation many committees whose duty it is to collect and present to the So- ciety at the conventions and in its journal the latest data along the lines of their various endeavors. They of- fer to the members of the Society an authoritative source of research and a solution for many problems. The motion picture industry benefits from these various endeavors of the So- ciety from the standpoint of better equipment with which to work, stand- ardized methods of procedure and technique resulting in a savings with the ultimate aim to aid in the pro- duction of better pictures and im- proved theatre conditions. The Society holds two conventions a year in various cities. It is ex- tremely pertinent to state at this time that the Spring Convention of 1931 will be held in Hollywood, California, during the week of May 25th. At these meetings papers are presented and discussed on various phases of the industry, theoretical, technical and practical. Demonstrations of new equipment are also often given. In all, a wide range of subjects is offered and in many instances the authors are the highest authorities in their distinctive lines. In 1930 the Society discontinued the publication of its Transactions, which appeared only following each semi-annual convention. In its stead was substituted the monthly Journal of the Society. At the Spring Convention of 1928 in Hollywood the Pacific Coast Sec- tion came into being. At that time Seven EXCHANGE CO-OPERATION It is not the intention of this so- ciety to show any partiality among film exchanges, nor to give preference to any one particular apparatus, but when it comes to our attention that unusual efforts are being made to eliminate some of the annoyances of which the projectionist has to con- tend with we feel that the sponsors of these acts should be commended for the w’hole-hearted co-operation they have shown us. The Paramount Film Exchange in San Francisco has installed four splicing machines in their inspection room, which cuts, scrapes and patches film in five seconds — insuring a splice that will withstand excessive strain and so give us more confidence in the first presentation of a new show. Bro. Fred Sundquist of Chapter No. 16 has charge of the pre-view room at the exchange and is rendering val- uable assistance to the projectionists as well as to the exchange. Films are being renovated periodically and standard releases are kept in con- formity with specifications. SAN FRANCISCO LECTURE SERIES Prof. Lester E. Reukema has to date delivered thirty-three lectures to Chapter No. 16 and each one has brought enlightenment in some form or other to all of us. Copies of these lectures are distributed to all the members and are kept on file as a reference book. The professor is very thorough in his talks and when we consider that in the early days of sound pictures when we were not al- together familiar with sound appara- tus, his lectures seemed a little in- comprehensible to us, but now, in glancing back over what we have al- ready been through they throw a bet- ter light on the subject and the boys today are following the articles more closely. Not only that which is al- ready established, but new develop- ments in the sound industry are hold- ing the attention of every one. Pro- fessor Reukema is following new ad- ditional improvements in the craft and delivering up-to-date lectures to us weekly. We hope to have an un- usually large attendance from now on and occasionally a luncheon will be served prior to the opening of the meeting. there were approximately forty mem- bers enrolled, including men serving in various capacities in the motion picture field. At the present time there are approximately one hundred active and associate members. Since that time the Section has endeavored to hold periodic meetings presenting to the local members papers and dis- cussions on pertinent topics. The Section really functions as an open forum — and usually a general invi- tation is extended to the industry to attend and join in the discussions. To various projectionists for whom this resume of the Society’s activities Eight is written this general invitation is likewise extended. The affairs of the Pacific Coast Section are conducted by its officers, who include the chairman, secretary, treasurer, and a board of managers composed of two members of the so- ciety. There are also several com- mittees operating in close harmony with the officers. Meetings are held monthly and notices of such meetings are sent to each member. In closing, the society would like to extend to the readers of “Loud- speaker” a cordial invitation to take part in the meetings and discussions of the Pacific Coast Section of the S. M. P. E. The Ortho-Krome Screen By T. L. DOWEY Electrical Research Products Inc. The screen is an important factor in controlling the results obtained with talking pictures, and Electrical Research Products, Inc., has nat- urally given careful study to the characteristics of different types. While this investigation resulted in several commercial types being rat- ed as acceptable, the form of screen now known as ortho-krome was found to have certain outstanding merits which make it unique. It is the in- vention of Mr. A. B. Hurley, a New York physicist and authority on phy- siological optics. It is of interest to note that in addition to possessing satisfactory acoustic qualities for sound picture use, it is light in weight, flameproof and permits a sav- ing of projection lamp current. How- ever, its distinctive feature is the manner in which it eliminates eye- strain by the application of certain principles of physiological optics. In addition there is a decided improve- ment in the appearance and definition of the picture, especially when col- ored. It is well known that the compon- ent colors occur in different propor- tions in light coming from sources of different nature, such as the sun or the various kinds of artificial lights. Although two sources may both be ra- diating the same total quantity of light. The quality of the light is, therefore, not necessarily iden- tical. For example, taking sun- light as standard, a high intensity arc lamp produces blue and violet light in relatively large amounts, while red and yellow are prominent in the light from an ordinary incan- descent lamp. The eye functions best and is least subject to strain when exposed to daylight or to illumination having a spectrum resembling daylight. Un- der high intensities the pupil of the eye involuntarily contracts, to pro- tect the eye against damage, while under low intensities it enlarges so that the retina will receive enough light to permit distinct vision. The reason why daylight or similar illu- mination does not cause eye strain within the ordinary range of intensi- ties is because at each intensity the opening to which the pupil adjusts itself for protective purposes, is also enough to admit sufficient light for distinct vision. However, under illu- mination having a spectrum mark- edly different from that of daylight, this natural balance is upset, and when the pupil is opened sufficiently to admit the total amount of light necessary for distinct vision, too much light energy of the frequencies which are unduly prominent in the artificial source will be admitted to the eye. On the other hand, if the pupil is closed sufficiently to protect the eye against these excessive in- tensities, distinct vision will be inter- fered with. In this way artificial lights tend to produce conditions to which the eye can not fully accommo- date itself and eye strain necessarily results. The undesirable condition just de- scribed had never been taken into consideration in the manufacture of motion picture screens until Mr. Hur- ley initiated the experiments which led to the development of the Ortho- Krome screen. The reflecting surface of this scren is treated with pigments in a carefully predetermined manner, so as to compensate for the type of light with which the screen is to be used. The result is that the reflected light does not unduly tax the adjust- ing powers of the eye so that eye strain is eliminated and at the same time the apparent brightness and definition of the picture are increased. The projection lamp current can con- Continued on Page 20 Nine I Visual Education In San Francisco By FRANK W. COSTELLO With the introduction of sound in motion pictures three years ago the status of the projectionist has been somewhat changed, but it has been proven that the projectionists were ready for the emergency which con- fronted them and met the situation well qualified to undertake the addi- tional responsibilities placed upon them. As far back as twenty-five years ago, synchronized sound with motion pictures were placed before us, and although the results were not gratifying, the optimists did not lose faith and in 1913 came forth with what they considered a great im- provement in synchronized appara- tus, only to find that the audibility of this new device (invented by Edison) did not respond favorably to a criti- cal audience and so the reality of sound pictures faded from our minds — at least temporarily. From the time that motion pictures were first placed on a commercial basis the realization that projection- ists (or operators, as they were then called) would play more important roles in the future, were apparent in the minds of some of our leaders, and although most of us working at the craft today may recall to mind many who have worked diligently for the welfare of the projectionist. A. P. S. Chapter No. 16 wishes at this time to mention Bro. W. G. (“Pop”) Woods, who, from the inception of motion pictures, has taken an active part in promoting the interests of men confined in the small enclosure, who had the major responsibilities and received the least recognition until recent years. Bro. Woods pre- dicted years ago that the projection- ists would be in the future called upon to perform duties that were incon- ceivable at that time. The plans he proposed and made effective included the adoption of an educational pro- gram whereby the men were not only kept abreast of the times, but given an insight to the future. Of his time Ten and literary ability, Bro. Woods has always given freely and generously and the boys feel proud and honored to have a man of his caliber in our midst. Always an educator, directly or in- directly, a few years ago “Pop” ac- cepted a position with the Visual Ed- ucation Department of Public Schools as chief of projection. The equipment of this department consists of two machines, stereo and spot with M. G. sets in the high schools and some fifty 35 m.m. portables in the elemen- tary and junior high schools, and a reserve supply of both 35 and 16 m.m. machines at the central office, which, with the necessary films are distributed to schools not having a projector of their own, and Bro. Woods personally operates from four to six shows each day when the films are leased and must be shown to as many schools as possible in a short time. These pictures are all of an educational nature, often consisting of a horticultural achievement, de- picting the propagation, blending and natural growth of fruits, flowers, etc., through interval exposures ex- tending over a period of months, en- abling the students to grasp their problems clearly and in a short space of time through their undivided at- tention. Many other educational sub- jects are shown to the children through motion pictures such as the interior of manufacturing plants, graphical descriptions of chemical re- actions covering the known laws of physics and chemistry, etc. The Board of Education is very fortunate in having a man like “Pop” Woods as Chief of Projection in the schools, for in addition to his long experience as a projectionist he has developed a clear understanding of the educational requirements of chil- dren and is in a position to suggest the proper selection of reels to meet the occasion. Photo Electric Cells By RICHARD VAN SLYKER About the least known part of sound apparatus now used by the pro- jectionist is the photo electric cell. This unusual tube has been brought to its present state of perfection with- in the last few years. The photo effect phenomena was first discovered by Dr. Hertz, who, in 1887, while experimenting with the actions of a spark gap, noticed that the impedence of his spark gap was affected by the radiations (the ultra violet ray) of another nearby experi- mental spark gap. Preceding Dr. Hertz an English experi mentor by the name of Willoughby Smith, while working with selenium resistances for transmission purposes, discovered in 1817 that the selenium he was using would change its resistance when exposed to light rays. Next in adding to the information of photo phenomena was Dr. Hall- wach who, in 1888, discovered the fact that certain negatively charged metals (surface charge) became less negatively charged when exposed to the radiation of ultra violet rays. Then, in 1889, Schmidt in Germany noticed that crystals of cuprous oxide (cuprite) used as electrodes, when immersed in a sodium hydroxide solu- tion became more positive when the solution with the immersed electrodes was exposed to light rays. After these men came the scientists Elester and Geitel who evolved the fundamental principles and theories of the photo electric effect in various minerals. These men practically completed the evolution of photo phe- nomena about 1905 and are respons- ible for the real advancement of the photo electric cell. Since their time the Arcturus and X-cell are the only notable contributions to the advance- ment of photo electronomy by virtue of their components. In the day of Elester and Geitel the vacuum tube which is now in univer- sal use for amplification purposes was unknown and instruments to use the currents and effects of the photo elec- tric cells were not to be had, and the only means of determining the actual presence of photo phenomena was a crude though sensitive instrument called a Horoscope composed of thinly beaten gold and silver leaves suspend- ed within a glass container. One of the contributing difficulties with which the early research work- ers were confronted with when ex- perimenting with photo sensitive ma- terials was that the underlying prin- ciples were hard to segregate due in the main to the three most prominent manifestations of the photo sensitive material which can be classed as fol- lows : (1) The actual emission of photo electrons from the electrically con- ducting body due to impinging light rays. This is true photo electric phe- nomena. (2) The ionization of the media (gas or element) surrounding the cathodes and anode causing a current flow due to the emittance of photo- electrons. (3) Changes in the media sur- rounding the cathode and anode due to changes in temperature and volt- age. Numbers one and two are produced by the action of light rays, and due to their nearly directly proportionate ratios are most useful in sound work. No. 3 is caused by excessive polariz- ing current in the photo electric cir- cuit and extraneous applications of heat transmitted by either light ray or metallic connections. We now have in commercial use three distinctly separate types of pho- E ltm* ■■> . !-■».. • >fll BH M ffl ^ SB ffll i ’t - I! ‘ 1 O Vs |1A .1 ( i ti ft iTT ' Mill WESTINGHOUSE THERMIONIC TUBE CONTROLLED THEATRE DIMMING CONTROL BOARD Complete Description In This Issue June, 1931 Twenty-five Cents Complete Service for your Projection Room or your Theatre Intelligent, Concientious Co-operation National Theatre Supply Co. Executive Offices -- 92 - 94 - 96 Gold Street, New York ❖ I A - SUPER - SPOTLIGHT HIGH INTENSITY ARC— 75 TO 125 AMPS. Equivalent to Three of the Ordinary Spots in Power i i i Gives Pure White Light i i i Round Spot Without the Usual Rainbow and Neg. Carbon Image 1 i i Convenient to Operate and Capable of Producing a Number of Beautiful Effects i i i For Further Information Apply to NATIONAL THEATRE SUPPLY CO., CITY i i i HALL & CONNOLLY, Inc., NEW YORK One The Ashcraft Air Blast Projection Lamp Efficiency \ Due to careful design — the result of long experience. /Freedom from necessity of replacement parts and Economy excessive maintenance costs. No condensers to (break. Carbon consumption IS NOT excessive. THE ASHCRAFT AUTOMATIC ARC CO. 4214 Santa Monica Boulevard I. A. T. S. E. EMBLEMS 4 inches in diameter in blue and silver enamel with attachment for fastening to your radiator, and with the number of your own Local. Price $1.50. Ask your Local Secretary about them. CLYDE W. SHUEY, 51 Rose Avenue, Venice, Calif. Manufacturer and Distributor T'vjo Quality, Workmanship and Service f i For A-l Projection i Keep Your Projection 1 Machines in First Class Condition, by Having Them Serviced Regularly by Projection Equipment AND Maintenance Co. ALL WORK DONE BY FACTORY METHODS AND FULLY GUARANTEED WESTERN ELECTRIC PROJECTOR MOTORS AND GENERATORS RECONDITIONED AND GUARANTEED 111 GIVE US A TRIAL PROJECTION EQUIPMENT AND MAINTENANCE CO. 3608 Farris Drive, Culver City, California C. M. (Chuck) Fowler L. M. (Louie) Wutke Phone Culver City 3869 Phone WHitney 4652 R3 h ree Modernize Your Powers! With the Knowles Rear Shutter Attachment The Original Rear Shutter for the Powers Projector Full Announcement Will Appear in Near Future Remember! You need not discard your Powers Projector in order to enjoy the benefits of the most modern development of projection engineering ♦ . ♦ Your Dealer will supply you with full information ♦ Vou r A Technical and Educational Publication. Devoted to the Western Projectionist and his Progressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G. CROWLEY H. E- ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE l26/» Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Pleasant 7332 Circulation JAMES B. GILLARD, Oakland Editor FRANK W. COSTELLO, San Francisco Editor 1436 Delaware St. Berkeley, Calif. 1230 Hyde Street, San Francisco Technical Editors: A. C. SCHROEDER, D. B. McGOWN and R. H. McCULLOUGH Volume II. JUNE, 1931 Number 6 Introduction of Vacuum Tubes to Theatre Lighting Control By E. W. Anderson, A. P. S. No. 7 7 A Reply to Mr. J. B. G. By Gertrude Munter, Local No. 6, A. F. of M. . 11 The Other Fellow’s Number By J B. G 13 Photo Electric Cells in Sound Projection By A. J. McMaster, G. M. Laboratory .... 15 Craft Technical Data By A. C. Schroeder, A. P. S. No. 7 21 Things in General By the Editor 24 Pin Spots 25 Chapter Doings — California Chapter No. 7 and San Bernardino Chapter No. 19 26 Secretarial Comments — By Fred L. Borch, Sec. California Chapter No. 7 . 27 Wave Chart 30-31-32 Published Monthly, Sponsored by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Blvd., Los Angeles, California ^i * ,1 .'ii • ' -- i iV- J * § % Fig. 1 —Remote Control Board Seven used to operate the circuits of one col- or, the top, amber; the middle row for red and the bottom row for the blue. Each individual control circuit con- sists of two telephone switch keys, an indicating lamp, five pre-set poten- tiometers and an individual control potentiometer. The switch key lo- cated at the top of each control sec- tion connects the circuit directly to a hot bus on one throw, the other throw connects to a color master control. The middle position is the off position The individual potentiometer con- trol corresponds very closely to the standard dimmer control in that by means of it the intensity of the lights may be varied from full bright to blackout or set at any intermediate position desired. However, in addi- tion to this it is possible through the color master control to bring an en- tire group of lights from blackout to any desired pre-set intensity by merely operating the color master as- sociated with this group of lights Fig. 2 Showing Control Levers and Pre-Set Keys for the circuit. The switch key im- mediately below this is used, on one throw, to connect the circuit through an individual control potentiometer so that the lights may be varied inde- pendent of any pre-set position and the other throw of this key connects the circuit through the pre-set poten- tiometer so that the lights may be varied automatically by means of a master control either motor driven or manually operated. Eight from the blackout to the full bright position (Figure 3). By the above it is meant that, for instance, the main red ceiling lights might be set for full brilliancy, the front ceiling lights for half intensity, the rear ceiling lights for three-quarter intensity and so on through the balance of the audi- torium lights and these circuits brought to their respective predeter- mined intensities by means of the color master. This was not possible in the old type of control due to the fact that when the individual dim- mers were interlocked on the color master control it was only possible to bring the circuits to some desired in- tensity as a group, unless the indi- vidual dimmer controls were disen- gaged from the master control at dif- ferent points, a slow, inefficient op- eration. Due to the fact that the tube type of control uses an electrical master instead of a mechanical mas- ter, it is possible to obtain the above mentioned flexibility of control which was heretofore impossible. The operation of the pre-set fea- ture of intensity control is as follows : Each circuit is provided with five small potentiometers which may be set up before a performance for any desired intensity. These potentio- meters are then operated through a master control which may either be run by means of the motor drive provided or by means of a hand wheel so that the effects may be changed from one to another at any desired speed. This control is so sim- ple that by the operation of a single telephone key which controls the mo- tor drive the entire lights for stage or auditorium may be changed from one effect to another. Furthermore, this change is made in a proportional manner since the intensities of all the circuits which are to be changed* commence to vary at the same time and the period of transition is ended when the motor drive reaches the next succeeding effect. A color master control is obtain- able by means of the larger potentio- meters which may be noticed on either side of the master control section. These color masters allow complete color control of the group of lights with which they are associated. In addition, a grand master is also pro- vided for the auditorium lights so that the entire house may be dark- ened by means of a single potentio- meter or may be thrown off or on by the operation of the single tele- phone key located near the top of the master control section. In both of the above operations these lights are Fig. 3 Tube Control Equipment Nine automatically brought to the pre-set position, previously determined by the operator so that it is unnecessary for him to manipulate any of the indi- vidual controls in order to reach the effect which he desires. In addition to the auditorium con- trols, the projection room control board is provided with four controls, at the right hand section, which take care of the lighting for the footlights, the first border, the orchestra floods and the stage floods. These lights were put on dual control so that they may be operated either either from the projec- tion room or the stage. The control for each of these circuits and for those of the stage board is similar to that pre- viously described for the auditorium circuits. In addition to the above mentioned preset control, the switchboards are also provided with five pushbuttons, located in the center section, by means of which it is pos- sible for the operator to flash from one effect to another should he desire to do so. Thus by opera- mers which are used in conjunction with this equipment are shown in Figure 4. Their action is as follows : The load circuit from the lights is taken through a reactance type dim- mer which operates similar to the standard reactance dimmer. That is, the reactance in the lighting circuit is varied by changing the saturation of a reactance coil. This saturation is changed by varying the amount of direct current through a coil located Simple schematic wiring d/agram op R T PR! CAL CIRCUIT THERMIONIC Type THEATRE SWITCHBOARD individual POTENTIOMETER tion of a small pushbut- ton it is possible for the operator to change the ^ entire lighting of either auditorium or stage and have all the circuits come to a predetermined in- tensity. This marvel of lighting control has been made possible through the broadening of the field opened by the use of the radio tube. The various controls above operate on a vacuum tube control set so as to change the output of this set from a minimum to maximum or any desired inter- mediate point. A photograph of the tube control equipment is shown in Figure 3. The reactance type dim- Ten REACTANCE DIMMER Fig. 4 Wiring Diagram of Reactance Type Dimmer on the reactance dimmer. The va- cuum tube control equipment enters into the picture by supplying the direct current to this third coil. This is accomplished as follows: A 115- volt, 60-cycle supply is fed to a trans- former in the tube control set, the output of this transformer is rectified by means of two of the tubes in the set and from this point is impressed (Continued on Page 33) A Reply to Mr. J. B. G. By GERTRUDE MUNTER Local 6, A. F. of M. I read with great interest the clev- erly written article in the March is- sue of the Loudspeaker by J. B. G., “Give the Musicians a Break.” Be- fore I comment on the many inter- esting remarks, may I compliment Mr. J. B. G.? He is some “ink sling- er.” Having been an organist for many years (if I told you how many, you would know how old I am), I have had the pleasure of working with many projectionists, and have found them a courteous, studious and kindly bunch of fellows. Many times as I have sat at the organ receiving the plaudits of the audience, I have thought how little the people realized how futile would have been my ef- forts were it not for the ever-watch- ful man up there under the roof who helped to pull me over, and how little credit has ever been given you boys for the success of the show. Without you, it could never go on, and still no one ever sees you, nor even thinks of you, unless you happen to have a film break, when they greet you with loud jeers and stomps. Lucky for you that you could not hear them, or were too busy to be bothered. Now that the talkies have descend- ed upon us musicians like an ava- lanche and literally swept us off our feet, the blow to myself was a severe one, not so much from a financial standpoint as for some of our mem- bers, for I have my husband to fall back on, and have a roof over my head and three squares a day, but be- cause I had spent years of study in an endeavor to perfect myself on the theatre organ; and to have it taken away over night, well — I just can’t tell you what a shock it has been. But think of those clever and able organists with wives and children de- pendent upon them, men who know no other line of work but music, who It is with considerable pleasure that we note the ready response of the thinking , musicians to the peace overtures of pro- < jectionists. There is no quarrel between ] the two groups of workers. Instead, there , is a keen mutual respect and admiration. • The well ordered program in any theatre , requires the combined efforts of the EN- - TIRE theatre personnel to correctly en- ] tertain the patron. Our thanks to Miss , Munter. She gives voice to the true feel- • ings of her fellow artists. — EDITOR. have found themselves “out cold.” no- where to go, nothing to do — it is ab- solutely appalling. And this goes for the orchestra men as well. Some of our best mu- sicians are driving taxis, but many of them are living from hand to mouth, just managing to get by. Pathetic is not the word for their condition. The average musician is a sentimental, temperamental person, wrapped in his work, taking no thought of the morrow, and now his work, his very life has been taken away from him. What worse could happen? The main point of this article is to thank Mr. J. B. G. for his wonderful thought expressed wherein he says: “If the organist or orchestra is to play the titles of the news or the main title of the featui’e, show them the courtesy of hanging onto the fader like the proverbial leech until the cor- rect split second. Don’t break into their only too few minutes of effort without warning, without allowing them to diminish to a suitable close.” I am frank to say it brought tears to my eyes when I read the tender thought for us. I shall pass this ar- ticle of yours along, with the request that a more capable pen than mine answer it in the way it deserves. But for myself, I cannot begin to express my deep appreciation of your article and the sympathy you extend. All hail, Projectionists, I salute you! E l even HELPFUL DATA Secured by Frank Wood, A. P. S. The mysteries surrounding voice amplification are manifold; in fact electricity in its various forms is mys- terious to most people. The secret of voice amplification lies mainly in the vacuum tube, containing the three elements, namely, filament, plate and grid. We are told that electrons (negative part of electricity), are emitted from the heated filament and are attracted to the plate which is charged positive. The grid is charged negative, the degree depending on the incoming signal, which would make it vary from a low to a high negative and vice versa, so naturally as un- likes attract and likes repel, some of the electrons never reach the plate, in- stead come in contact with the grid and are repelled back into the fila- ment. The grid will always remain negative providing the incoming sig- nal is somewhat lower than the grid bias. The voltage of incoming sig- nal as read on a volt meter is the ef- fective voltage, but it is the maximum voltage which we must consider in or- der to use the proper grid bias, so, for an expectant signal say of 12 volts, to obtain best results, we should use a grid bias of 12x1.4142 or 16.97 volts or approximately 17 volts. Di- viding 12 by .7071, which is the sine of 45 degrees, will give the same re- sult. However, if the signal should exceed the grid bias, the grid will be- come positive and attract electrons. This flow of electrons in the grid cir- cuit would produce a grid current causing distortion, so it is absolutely necessary at all times to keep grid bias more negative than any expect- ant signal. The grid acts as a valve to control the flow' of electrons to the plate, thereby governing the ampli- tude of signal. All this sounds like so much Greek to most people who are not interested Tave I've in amplifiers, yet a graphical demon- stration will bring a little more en- lightment. Such a demonstration we had the pleasure of witnessing last week. Brother Woods, who is Chief of Projection for the San Fran- cisco public schools obtained and pro- jected for our benefit two reels of mo- tion picture produced by General Electric Company, which explains graphically the action of vacuum tubes. With the circuit completed, showing the wires running from the “A” battery to the filament, also the wires from the “B” supply feeding plate through primary of transform- er, grid return going to negative “G” battery, thence to negative or ground, input signal through microphone, and then in order to visualize more clearly through motion pictures, wre have the apparition of the electrons fulfilling their duties of amplifying and carry- ing signal from vacuum tube to trans- former, where again we see the mag- netic lines of force in actual motion, as the “A. C.” voice current is ampli- fied and sent on to the following tube, electrons increasing in size denoting an increase in amplification. While it may not be necessary for us to rely on motion pictures to explain all of the intricate problems which will con- front us, still we must admit they will be a big help and some of our subjects through the use of motion pictures will be self explanatory. iii MACHINE SPLICING TIP The following timely suggestion was submitted by Bro. E. B. Winn, Jr., of Chapter 19, A. P. S.: “Projectionists using the Griswold Film Splicer will find that if cement be applied to the under side of the top or right hand piece of film right after the brush is drawn over the scraped end, the splice will hold much more firmly and cannot be pulled or picked apart a'fter it has dried. I have found that splices made on tint- ed stock would pull apart especially easily unless done the above way.” The Other Fellows Number By J. B. G. The well-known twin enemies, Sus- picion and Scepticism, have a more obese edge on the A. P. S. movement than most of us deign to admit. When these gladiators are in the ring they are favored by a Chicago “count.” And if frankness is not out of place, let us stumble into their re- spective training camps and study their form. If they prove as for- midable as we now think they are we should be wary of them in future meetings. The reason Suspicion and Scepti- cism still exist to gnaw at us, under- mine our foundation and slow up the growth of our Chapters, is simple. And to allow their continuance in our midst brands us the same. We have each other’s number! This may sound like levity. It is not. Often we do not respect those whom we know too well. It is a natural law, a frailty, a weakness of mankind most difficult to overcome. In our profession we avidly accept advice from strangers which we would scorn from friends. Assuredly we are brothers; and there are none of us who would not go through the fabled brimstone for the other. But notwithstanding, we have each other’s number. And the possession of the numeral makes us bury our heads in the childish sands of cynicism even though our brothers have something worthwhile to offer. Brother Joe Zuke, of Pottsville Chapter, (where they have Brother Joe Zuke’s number), can visit Kettle- town Chapter (where Joe’s number is only conjectured), and deliver an address on keeping the equipment clean which will be wowingly re- ceived. The points brought out by Brother Zuke are worthwhile, logical, and adherence to them mighty bene- ficial. Allow Joe, however, to release the same logic before his own chapter, and what will be the reaction? Joe is blushing before he has uttered fifty syllables. And before he has mouthed a hundred he would trade his two-man shift position for a one- man brush job if he could be home in his little white bed. Why? Why, be- cause Joe is hearing the mental “asides” of his listeners who have his number. Joe, it seems, before the war, was discharged for maintaining a dirty projection room .... Joe, it seems, was once under charges for damaging a print on a Turpin-eyed rewind .... etc., etc. Is Joe a hypo- crite? Unless we are unfair enough to use the word in the widest conno- tation— no ! He is like the minister who avoids his wife’s eyes while delivering a ser- mon. His words are helpful, good and true. But he realizes during the flow of his august words that his mate may be reminiscencing over their years of connubial association and possibly is reviewing certain se- quences that he would cheerfully for- get. She has his number. So he would prefer that she sat in a more distant pew so that he couldn’t see the half-smile that verticals the cor- ners of her mouth. Is this minister a hypocrite? Not this one. For another hypothetical example consider a projectionist administer- ing a protest against change-over film mutilation. He has, to cheer him up, the knowledge that his own theatre formerly displayed so many change-over scratches that it resem- bled a racing turf bulletin board on a rainy day. Still the brother is not trying to put anything over. What he says is trenchant and the saying of it helpful. Couldn’t the projec- tionists who had his number have given him the benefit of the doubt? Couldn’t they have kept their poker- faces with less visible effort — allowed Thirteen Toronto, Canada, Holds Examination Chapter No. 9 Members Make High Ratings According to examinations so far held under the Provincial Treasurer’s Department, the standard of effi- ciency of motion picture operators is very high. The operators have been under examination for some time past, and nearly all of them have passed the practical tests in the oper- ation of sound and silent projection machines. Over most of the Prov- ince, the written examinations for operators have also been held. At the Parliament Buildings, the written examinations for Toronto operators was held. Nearly a score of candidates took part in the exam- inations, which included difficult tests about the theoretic and prac- tical phases of projection for both speaking and silent pictures. The advent of sound pictures originally inspired these examina- tions for motion picture operators. The technique which the “talkies” require for projection is far more complicated than that which the old silent pictures demanded, it is said. Hence the necessity for the examina- tions on physics, optics, chemistry, acoustics, etc., which made a score of young men chew ends of pencils recently from 9 o’clock in the morn- ing till around 4 o’clock in the after- noon. Maybe it wasn’t a matter of optics, acoustics, physics, etc. The contents of the examination paper were not divulged. But he did get this as- surance from an official of the de- partment : “The moving and talking picture operators of the Province have already shown a very high standard of efficiency.” The same official was quoted as saying that most operators have been studying the theoretic and technical factors in their work very intensively these many months. They have even formed study groups and met to- gether at regular intervals to wrestle with the intricacies of problems which might be presented at exam- ination. The examination consisted of 542 questions, covering all branches of the industry. In its entirety it comprised the most complete set of technical questions ever presented at a similar occasion. The Toronto men are to be congratulated upon their remark- able record. him to regain his seat feeling at least fairly comfortable? Make the test on your chapter some time when things are dull. But don’t expect too much. When you have a fellow’s number the tendency is to prove the possession. Especially when a little thing like a chuckle will cinch the point. Doubtless there isn’t a potential mistake which hasn’t been made by each of us at one time or another. If a brother has the courage to talk constructively let us not drag his family skeleton from the obsolete ree- f’s u rt e e n tifiier room. Give him credit and en- couragement. Even though his ver- balism is tinctured with a sauce made of apples, his is still a noble gesture. Many a policeman if stripped of his brass-buttoned uniform would not be a sensationally virile specimen ; but in his uniform he commands respect. Let us wear our uniforms to hide our bow legs and sunken chests. It is not hypocritical. It is showmanship. And by so doing we’ll become more original in allowing our familiarity to breed something besides contempt. (Finis)' Photoelectric Cells In Sound Projection By A. J. McMaster, G. M. Laboratory Not unlike other modern engineer- ing developments, the art of synchro- nized sound pictures has been made possible by the perfection of acces- sory apparatus first developed for use in other fields. Although the original concepts of synchronizing sound with motion pictures using both the phonograph disc attachment and the sound track on film are many years old, the present status of this new industry is due principally to the availability of the modern radio tube, loud speakers, and other elec- trical, optical, and mechanical appa- ratus. Among the devices that have contributed in a large measure to the success of the sound moving picture development is the alkali metal photo- electric cell. For many years the selenium cell was practically the only light sensi- tive device available for experimental work in reproducing sound fi'om film. During the last decade, however, many important developments have been made in light sensitive tubes. The particular requirements of such a tube for use in sound picture equip- ment are many and varied and today have been met with a certain degree of success. For greatest sensitivity, noiseless operation, speed of response, and consistent performance, the al- kali metal photoelectric cell has re- placed practically all other forms of light sensitive devices in sound pic- ture work. Photoelectric Cell Action Whereas the selenium and similar actino-electric cells depend for their operation upon the variation of elec- trical resistance of a metallic com- pound, the action of the photoelectric cell is quite different. In Figure 1 a schematic illustration of the action of a modern type of cell is shown. If light is allowed to fall upon the sen- sitive surface, electrons — i. e., unit particles of negative electricity — are emitted from the surface and are at- sens/ t/tr surface -e* O (i o Figure 1 tracted to the anode due to the polar- izing action of the battery in the ex- ternal circuit. This flow of electrons from the sensitive surface to the anode and continuing through the ex- ternal circuit comprises the photo- electric current. There are two general classes of alkali metal photoelectric cells. The vacuum type, as the name implies, contains no gas. The gas-filled cell, however, is filled at a low pressure with inert gas such as helium, argon, or neon. In this type of cell, the pho- to electrons ionize the inert gas in their passage from the sensitive sur- face to the anode. The resulting ionization current is added to the electron current, giving a larger to- tal photoelectric current than in the vacuum type of cell. Photoelectric cells of maximum sensitivity are therefore of the gas-filled type. The magnitude of the photoelectric current in the gas-filled cell depends upon the specific surface sensitivity, color of light, the volume, pressure and nature of the inert gas, cell volt- age, and the total light flux entering the cell. In the vacuum cell the cur- rent depends only upon 'the surface sensitivity, color and amount of light, and to a certain extent upon the cell voltage. As there is no ionization in the vacuum cell, the sensitivity does not materially increase after the sat- uration voltage is reached, and the cell is not critical with respect to op- Fifteen erating voltage. This characteristic is illustrated in Figure 2 (Type AV). Where high sensitivity is not import- ant the vacuum cell can, therefore, be conveniently used. However, the sensitivity of modern vacuum cells is but approximately one-fifth of that of gas-filled cells and the latter are used in most sound on film equipment. Neiv Visitron Types To meet the optical and mechanical requirements of various sound head attachments for standard projectors, a number of new types of Visitron cells have been developed, seme of which are shown in the accompany- ing Figure 3. These cells, known as Visitron type “A” (gas-filled) and type “AV” (vacuum), represent the most recent developments in alkali metal photo- electric cells. They are the result of several years of intensive research work, and have a number of points of superiority over previous types. The inserted metal plate construction as contrasted with previous forms in which the sensitive material was placed on the inner surface of the glass bulb, permits greater uniform- ity in the physical assembly, and a cell of very much greater sensitivity to the small changes in light intensity produced by the sound on film record. Furthermore, the new type “A” and “AV” cells have much longer life (a Sixteen life expectancy of well over a year) and require lower operating voltages than the cells previously supplied for sound equipment. Of particular in- terest to the exhibitor is the fact that there is practically no deterioration of the new cells when they are stored as “spares” or emergency parts — that is, they have extremely long shelf life. In selecting a cell most suitable for a particular projector, the optical system and cell must be so selected as to permit the greatest transfer of light energy from the exciter lamp through the sound track on the film to the sensitive surface of the cell. There are several types of exciter lamps available having different cur- rent and voltage ratings, as well as over-all dimensions of filaments. The lamp, optical system and cell should 58AWB 53AWB 58 A 59A-59AP 7lA 75 A 79A Figure 3 be co-ordinated to obtain the sharp- est and strongest light signal from the sound track. The cross-sectional area of the beam of light from the film to the cell is not important, but due to the fact that no part of the film is perfectly transparent but does have a diffusing action on the beam, the cell should be situated as close to the film as is convenient. In other words, it is of cardinal importance that the maximum light passing CELL CURRENT— MICROAMPERES — VIS CURREK TRON ce T— LIGHT — ,1s — TYPE FLUX CH $ A » A\ XRACTER STICS K r _ - — _r«^p.V — ' LIGHT ELUX— LUMENS Figure 4 through the film should reach the sen- sitive surface of the cell. Electrical Characteristics In Figures 2, 4 and 5, the princi- pal electrical characteristics of Visi- tron type “A” and “AV” cells are shown. In Figure 2 the specific cell; sensitivity in micro-amperes per lu-! men is plotted against cell voltage. ! As the voltage is raised the sensitivity; of the gas-filled cell increases rapidly; until the curve rises almost vertically/ If the voltage is raised above this crit-1 ical point, the cell “spills over” into a state of cumulative ionization or glowing. In this condition the cell is inoperative and is subject to serious damage. The maximum safe operating volt- age of the gas-filled cell depends upon the amount of light energy entering the cell. With greater light intensity the operating voltage must necessar- ily be lower to prevent cumulative ionization. All Visitron type “A” (gas-filled) cells are intended to be operated at 90 volts or less. In ap- plications where the light flux ex- ceeds 0.2 lumens, the voltage applied to the cell should be less than ninety. In all present types of sound equip- ment the light intensity is such that it is possible to use 90 volts on type “A” cells. Due to the fact that their sen- sitivity at this voltage is from two to five times that of older types, it is generally found that ample volume is obtained with considerably lower voltage. In many theatre installa- tions using the new cells, the volt- age required is not more than 25 or 50 volts. This permits raising the cell voltage in the later stages of the cell’s life, thereby maintaining uni- form cell output throughout the en- tire useful life of the cell. To obtain the maximum benefits from type “A” cells, it is advantag- eous to be able to independently ad- just the cell voltage on each projector. Many types of equipment provide such cell voltage control. Where this adjustment is not available, a simple cell voltage potentiometer can be eas- ily installed at very little cost. Such provision makes it possible to match O 5 CO .OR RESP (NO DNSE OF DRAWN TO HUMAN SAME VERTI EYE AND Al SCALE) TYPE "A” CELL 2f < f ;l 5000 6000 7000 WAVE LENGTH OF LIGHT— ANGSTROM UNITS Figure 5 the volume from each machine and to bring the fader setting to the mid- dle of the dial. The use of too high cell voltage re- sults in lower volume, poor frequency response (loss of the high frequen- cies), background noise, and cell noises in the form of a hissing or rushing sound. Moreover, the use of excessive voltage on the cell greatly shortens its life, resulting in the ne- cessity for early replacement. Manufacturing Process Barring such misuse, however, properly pumped and prepared gas- filled cells should give hundreds and even thousands of hours of consistent service without perceptible deprecia- Seventeen Camera Silencing Steps Taken The Producers-Technicians Com- mittee of the Academy at its regular quarterly meeting heard reports on camera silencing, the standard re- lease print survey, cue sheets, film processing, supersensitive film, and other technical developments in the industry. N. C. Levee presided. At the meeting it was reported that sixty first cameramen, representing all Hollywood studios, had replied to the questionnaire sent out in March by the Camera Silencing Subcommit- tee. 91% of the replies advocate strong efforts toward the develop- ment of cameras which would not re- quire blimps or covers of any sort. 52% of these replies urged such ef- forts in strong terms. The weight of the blimps in use was condemned by 90% of the re- plies; the bulk by 87%. 55% said the blimps made focussing difficult, and 73% said they crowded the sets uncomfortably on close-ups. Prac- tically every type of camera cover in use in Hollywood was criticized for one or more of these reasons. At the meeting it was resolved to bring this situation to the attention of the camera manufacturers and in- quire what efforts are being made to- ward the production of a silent cam- era. The committee will offer to have studio experts confer with the man- ufacturers in an endeavor to advance such efforts. The committee expressed its appre- ciation of the co-operation of the American Society of Cinematogra- phers, and of the International Pho- tographers of the Motion Picture In- dustries (Local 659 of the I. A. T. S. E. and M. P. M. 0.) tion. In this connection it is interest- ing to note that during the manu- facture of highest quality photoelec- tric cells for sound on film equipment, the pumping period for every cell is from fifty to seventy-five times that of present-day radio tubes. The equipment used consists of the most modern and effective vacuum pumps, gauges, and accessory apparatus known, and every cell is tested with the most sensitive of mirror type gal- vanometers for electrical leakage, voltage and sensitivity character- istics. To obviate difficulties with ioniza- tion of gas-filled cells it is highly recommended that sufficient amplifier gain be provided to permit the use of not more than the maximum safe op- erating voltage. The operating life of the cell is in this way very much extended and risk of damage to the cell and interruption of service is ma- terially reduced. A safe operating rule is to use the lowest possible cell voltage which will provide sufficient volume without excessive amplifier noises. Eighteen In Figure 4 are shown the linear light flux cell current characteristics for different operating voltages. Here again the increase of cell sensitivity with cell voltage is indicated. The ratio of the micro-ampere output per lumen of light flux at a definite cell voltage is a measure of cell sensitivity at that voltage. The linear response shown between light flux and cell cur- rent in the alkali metal photoelectric cell is of course an important factor in the undistorted reproduction of sound from film. In Figure 5 the color sensitivity of Visitron type “A” cells are shown and compared with that of the average human eye. The wave length of light corresponds to color, blue being at about 4700 angstrom units; yellow, 5800, and red, 6500. Type “A” cells are very much more sensitive in the red end of the spectrum than previous photoelectric cells. This fact is of considerable advantage in reproduc- ing sound from film, since the tung- sten filament exciter lamp emits a large portion of its light energy in the red portion of the spectrum. Delegation from San Francisco Chapter No. 1 6 Visits Oakland Chapter No. 12 By Frank W. Costello, A.P. S. In recent months the need for closer relationship amongst our A. P. S. Chapters in the West has become apparent. The voice of Loudspeaker has reiterated and stressed this fact on numerous occasions, realizing that this close co-operation together with the facilities that we have at our dis- posal on the Pacific Coast, will give the Western Projectionists the recog- nition that is due them. An example of this hearty friend- ship was manifested last evening when San Francisco Chapter No. 16 became guests of Oakland Chapter No. 12 at their initiation ceremonies. To go one better, Bro. W. E. (Bid) Horton, Business Manager of Rich- mond Local, who is also a member of Oakland Chapter, No. 12, invited the assembly to hold the meeting at his Berkeley residence. Our President, Frank L. Seavier, who has been through a long siege of sickness, was unable to accompany us, much to our sorrow, for his whole heart and soul is wrapped up in the A. P. S.; his great ambition is for the success and prosperity of our organization. He sent his regrets and wished us a good time. The delegation from San Fran- cisco was headed by Vice President Harry Everett (250 pounds of jocu- larity) , and a Stutz car that can climb the side of a building. Arriving a little early in Oakland, we parked on the road at an appointed spot at the intersection of Oakland and Berkeley and waited for the rest of the cara- van and a guide to take us through the foreign territory. Then began the climb up over the winding hills which became steeper with each mile. Fortunately, the two heavyweights — Everett and Heinhardt — were in the front seat, which lessened the danger of a back somersault. A look of con- sternation appeared on Everett’s face when an Austin passed us gracefully — saluting by throwing the spotlight on his face. We finally arrived at Brother Horton’s picturesque home on top of the hill, and after maneuv- ering around considerably, managed to park the twenty cars on the nar- row road. After the parking prob- lem was solved, we entered the house and everyone was made comfortable while Brother Lloyd Litton, Presi- dent of the Oakland Chapter, com- pleted the final arrangements prior to opening the meeting. The gathering was seated in a semi-circle in the spa- cious reception room when Brother Litton mounted the rostrum and called the meeting to order. With his opening remarks he laid great stress on the importance of holding joint meetings and social gatherings in the future, whereby the members of vari- ous Chapters may exchange ideas and talk over local problems. In this way, the Pacific Coast Chapters will ameliorate into a strong organization. A few remarks from Brother Rein- hardt had a tendency to strengthen this feeling. Dan O’Brien, service en- gineer from E. R. P. I., gave a very instructive talk on the care and main- tenance of motor generators. Dan not only has a beautiful flow of ora- tory, but is one jump ahead of any dear brother who tries to tangle him. It was very noticeable at this meeting that, although the members were eager to obtain knowledge and paid strict attention to the speaker — in or- der not to miss any part of his lec- ture, the spirit of fun entered into the occasion which was permissible at this sort of gathering and was a re- laxation from the boredom of excess schooling. A few questions were thrown at Dan in rapid succession — both of a practical and a joking na- ture, and were answered alertly in a like wise manner. Brother Everett let loose of a few witty remarks per- Nineteen JUST HOW CLEVER ARE YOU? This interesting series of puzzle diagrams has drawn to a close. It has created widespread interest and has no doubt benefited hum dreds of projectionists in all parts of the country. Because it either refreshed their minds concerning the various circuits presented or caused them to do some real research work which would, of course, increase their knowledge generally. You will all be interested to know the name of the projectionist who sent in the greatest percentage of correct answers. The clever brother is P. C. Young, who is a mem= ter of the projection staff of the Metro=Go!dwyn=Mayer Studio at Culver Citv, California. The award attesting his victory will be for- warded to him at once. Did you enjoy the puzzle series which were prepared by Bro. R. E. Clark? If so, write the Editor and perhaps we can persuade Bro. Clark to prepare another series. This sort of material helps to pro= mote friendly competition between the various projectionists in the West. LET’S GET TOGETHER AND URGE BRO. CLARK TO TWIST UP A FEW MORE DIAGRAMS FOR US TO DECIPHER! taining to Dan’s early life history, in- cluding his entry into sound engineer- ing, and Dan retaliated with a long list of denunciative adjectives de- scribing a certain “bootleg” set man- ufactured by a projectionist who seemed to have the confidence and ex- alted desires greater than the com- bined intelligentsia of R. C. A. and Western Electric, but the set finally passed into oblivion, dying a miser- able death. The stage was then set for the initiation of Brother Ander- son from Richmond. A description of this beautiful and touching cere- mony cannot be related. You must pass through this ordeal to become en- lightened. Brother Anderson went through with flying colors and is now a full-fledged member of Chapter No. 12, A. P. S. After the initiation, a long table was brought into the room and spread with a large assortment of eatables under the supervision of Mrs. Hor- T nv e n I y ton. who is a charming hostess. The feminine touch certainly adds qual- ity and refinement to an occasion like this. Brother Horton, our host, took his place at the head of the table and proceeded to cut the sandwich loaf, but for some unknown reason it would not respond to the sharpest knife that he could find. When three of the boys each handed him a saw, it finally dawned on Bill that someone was playing a practical joke on him, and about this time Mrs. Horton came in with an exact replica of the sandwich loaf minus the log of wood. The boys were hungry and did justice to the food, together with Litton’s amber fluid. The roosters were an- nouncing the break of day when we took our departure, Brother Litton escorting us to the ferry. A very pleasant evening was enjoyed by all, and we are looking forward to a visit from the Oakland Chapter in the near future. TRANSFORMERS TESTING FOR GROUNDS Locating grounds in transformers is done about the same as it is done in other apparatus. Testing low re- sistance windings such as the second- aries of filament transformers calls for no explanation. A buzzer rings through such a winding and can be used for finding a ground in it. When the test is to be made on an audio transformer we have the same prob- lem that we had when testing for con- tinuity; high resistance windings. Even here a buzzer can sometimes be used. If the ground is at one of the terminals there is no high resistance to be buzzed through and the buzzer will show the ground. One lead of the test circuit is placed on the trans- former terminal and the other test lead is placed on the core. A buzz shows this terminal to be grounded. When the test lead is placed on the terminal at the other end of the grounded winding no buzz will be ob- tained. The resistance of the wind- ing is so great that enough current cannot flow to operate the buzzer. If the buzzer is now removed and a sensitive voltmeter or a milliameter with a resistance in series is hooked into the test circuit the ground will show up. It is understood, of course, that a battery is used in connection with the buzzer and with the meters. The meters will show that there is a ground even if it is in the interior of the winding. When the inside of the winding is grounded it usually is a hopeless case as far as repairing the transformer is concerned. It is possible, however, to get by until another one can be ob- tained. A piece of insulating mate- rial is placed between the transform- er and the panel on which it is mounted. The fastening screws or bolts must also be insulated, either from the transformer or from the mounting panel. In cases where the transformer is mounted on a bakelite panel or on a wooden baseboard it is only necessary to remove the ground- ing wire from the core. When a pair of headphones and a battery are used for finding grounds a click is obtained when the connec- tion is made and when it is broken if the circuit is grounded. A very faint click is often obtained when the leads are placed on the terminal of a cir- cuit even when it is not grounded. This is easily distinguished from the click produced by a ground. Of course clicks produced by a grounded circuit do not all sound alike. When the test leads are placed on a termi- nal that is itself directly grounded the click will be louder than it would be if the ground is in the inside of the winding, and the resistance of the winding being around 20,000 ohms or more, but these can all be distin- guished from the slight click men- tioned above that was had when the T twenty -one leads are placed on the tei’minal of an ungrounded winding. Care must be taken to keep the hands or anything else that may be a slight conductor of current from getting across the test leads, as enough current may flow through this external circuit to give an indication on a sensitive meter or in the phones. Another point to watch is to be sure that the transformer is not grounded through some circuit to which it is wired. It is best to disconnect the circuit before starting to test for the ground. When testing transformers having a permalloy core the test current should be kept at a very low value. This applies mainly to the transform- ers in the 49-A amplifier, the three tube Pec amplifier used with the older ERPI sets and the input transformer in the 41-A amplifier. This point really should have been mentioned in connection with the tests for conti- nuity. Testing for grounds with a high value of current does not make so much difference, as no current will flow if no ground is present, and if the winding is grounded the trans- former is NG anyway, so there is not much to worry about. The reason for the low current is that DC in any amount will ruin the magnetic prop- erties of the core, it is then of less value than if it were made of ordi- nary core material. Two grounds in a transformer are not very likely to occur, but it is pos- sible for such a thing to happen. Merely insulating the transformer will not allow it to be used again, even for a short time, since the plate voltage is hooked into the grid cir- cuit through the two grounds. The wiring can be changed so as to use parallel plate feed. To do this hook a resistance from the plate to plus B, then hook a condenser from the plate to the P terminal on the transformer. Disconnect the B terminal on the transformer and connect it to the fila- ment or to the cathode of the tube. Mount the transformer on a piece of Twenty-two insulating material and then it will probably work. It will depend upon the position of the two grounds in the windings. If the thing won’t work hook the condenser to the G terminal instead of the P terminal. It should work now, although there will be a drop in volume since there is no step-up in the transformer, the primary not be- ing used and the secondary being used only as a grid choke. If it happens to be a push-pull in- put transformer the above still holds good. Should it be necessary to hook the coupling condenser to the grid it can be connected to either of the push-pull tubes, although one way might work better than the other. When the grounded transformer is one coupling a single tube to a line, or if it is a push-pull transformer in a similar position, and two grounds are present, parallel plate feed to the tube will remedy the condition when the transformer is insulated from the panel. It is usually necessary to re- move the ground connection in the low impedance line, if there happens to be one. I do not remember whether the line running from the 42 to the 43 is grounded or not, but the line from the 43 to the 200-A output panel is. When the ground connection can- not be found readily a 2 mike con- denser can be hooked into each side of the line where it leaves the trans- former. This is not the best practice as it does upset things somewhat, but it will enable the show to go on. Sometimes this trouble can be overcome by just reversing the leads to transformer. Take, for instance, a case where the transformer second- ary is connected to the grid of a tube and the other end goes right to ground. If the grid end should be- come grounded reversing the leads will place the grounded end of the winding where no harm will be done, that is, it will work. It is best not to leave it this way any longer than nec- essary, as a greater capacity exists SPASMS * , » o Managers who took up golf to relax their minds from business now con- tinue the game because there isn’t any. Doorboy (to singing assistant man- ager) : “Why don’t you change that tune you’re singing to ‘The Volga Boat Song?’ ” Assistant Manager: “And why should I, my lad?” Doorboy: “Well — you’re always working your drag ?” 0 Cross marks the spot where the body was found : “I just read a great technical ar- ticle.” “Yes? What was it about?” “Huh? That’s funny — I can’t think just now what it was about.” “I see. Who wrote it?” “Huh? Gee — I can’t think of his name now. But it was a pip.” “It must have been fine. I’m sorry I didn’t see it.” “Yeah. You ought to keep your eye out for his articles.” “Whose articles?” “Huh? Don’t be so stupid! — this fellow whose name I can’t think of.” Simile: As public as the contents of a service man’s brief case when he steps out to listen to the show. 0 Brother Huston : “Are you getting many of these Gilded Horse films?” Brother Friedman : “What-d’- yuh-mean: ‘Gilded Horse films?’” Brother Huston: “You know — Metro’s Golden Mare.” 0 Brother Miller: “The end of the comedy is full of punch marks — so just change over on the last one.” A good five-cent cigar would prob- ably do the country a lot of good ; but a manager who will buzz the fader down instead of up — if only for the sheer novelty of the thing — won’t do the country a bit of harm. — o — Pointed Questions : “There’s thirty feet to go — do you think you’ve got time to put in the right reel?” 0 “And furthermore — if you eggs can’t keep your shirts on we’ll install Cue-Meters and keep the observation ports closed !” “But it didn’t say ‘The End’ boss, it only said ‘Finis.’ ” from the grid of the tube when this connection is used than when the hook-up is normal. Should you have occasion to re- verse the wires, say for instance on the output transformer of a 43 ampli- fier, if you have only one 43 every- thing will be fine, but remember if you are using two of them that you must also reverse the wires on the other output transformer, otherwise there will be no sound. If you only reverse the leads to one of the ampli- fiers the currents from the two ampli- fiers will be 180 degrees out of phase. These currents will circulate through the secondaries of the two transform- ers but none of it will get up to the output panel. Possibly another point should be mentioned in connection with push- pull transformers when parallel feed is used. Each tube is hooked to its own P terminal on the transformer through a separate condenser, and separate resistances are used from the plate of each tube to the plus B wire. The B terminal on the trans- former is connected back to the cen- ter point of the filament transformer. Twenty-three THINGS IN GENERAL By THE EDITOR All knoivledge is lost that ends in the mere knowing; for every truth is a light given us to work by. Gain all the knowledge you can, and then be sure to use it to good purpose. — Ruskin. The foregoing quotation is one that should be filled with meaning to every thinking projectionist. Its truth is fundamental and is applicable to our profession just as much as it is to any other craft or individual. It states in a masterful way, which we could never hope to creditably emulate, what this publication stands for. An exchange of ideas among projection- ists is beneficial to the contributor and reader alike. A movement of this kind is cumulative and will in time exert a nowerful influence foi' good among the several chapters of our Society. I suggest that each mem- ber pass along througP the meun m of his publication any specialized knowledge that would aid his fpl^w craftsmen. It is the mission of this publication to aid western projec- tionists to gain a better understand- ing of their profession. There are no private motives in promotion and no other objectives whatsoever, other than that of carrying out that mission fully. On this basis we claim your full co-operation, and knowing the western projectionists as we do, we know that it will be forthcoming. * * * A convention of A. P. S. projec- tionists from western chapters in Hollywood. This is not only a pos- sibility but a probability. Many prominent men in Hollywood film cir- cles have offered the co-operation of their organizations to us in our effort to bring about a projectionists aca- demic convention. After consulta- tion with President Frank L. Seavier of San Francisco Chapter No. 16, and President Sidney Burton of Los An- geles Chapter No. 7, it was decided that the logical solution is to invite ‘T'wenty-four the projectionists from the various western A. P. S. chapters to come to Hollywood and spend a few days in the center of production. A lecture tour through the large studios would be an education to any projectionists in the country. A day’s trip through one studio would be well worth the co'd of the trip. We feel that the objective of all western chapters should be that of having a well informed membership. By fully informed I mean that each chapter wishes its membership to know every branch of the technical nhases of the industry. A short so- journ in Hollywood would help ma- terially in that direction. Chapter presidents please write in what you think of this idea. Let’s all get together and have an educa- tional conclave that will make his- tory. i i i The establishment of the Standard Release Print has made possible the abandonment of cue sheets for the projection of sound pictures, accord- ing to announcement of the Technical Bureau of the Academy of Motion Picture Arts and Sciences. Studios and exchanges have been notified by Lester Cowan, manager of the Bureau, that the distribution of cue sheets with prints mav be safe- ly discontinued. Spaces left for the purpose in the Standard Release Print will be used by the studios for any special information or statement of fader settings which the projec- tionist should have to run the show. Approval of this change in practice has been given by the Producers- Technicians Committee of the Acad- emy. The abandonment of cue sheets will mean a saving of several thousand dollars a year to each of the com- panies which have been sending them out with prints since the intro- duction of sound. The famous emporium of long runs, Grauman’s Chinese Theatre, was closed for three weeks this month. The brothers who enjoyed the forced vacation are Fred Weaver, Bob Babcock, Dave Koskoff and Rex Brown. i i i Bro. H. C. St. Clair is busily en- gaged in watching building opera- tions on his new home. He informed us that the house warming will take place in about 60 days. i i i Bro. J. 0. Ellery, Secretary of San Bernardino Chapter No. 19, writes that they are always happy to have visiting brothers at their meetings. Any members of the A. P. S. who can do so will find their time well spent. 1 i 1 Bro. M. H. Thoreau, President of Vancouver Chapter No. 11, A. P. S., visited in Los Angeles last month, to- gether with a party which consisted of four. At going to press, Bro. Thoreau had not been interviewed. We are sure, however, that he will make statements for publication in our next issue. ill Brother Wallace J. Maxon is now home from the hospital, where he is fast recovering from his iliness. i i i Stop the presses ! Last minute news tells us that Brother Harold Swanson is the proud Daddy of a boy born Sunday, May 24th. Cigars! IDIO(NON)SINCRASIES From San Francisco Harry Everett found out that the liquid in a Pyrene is not a good eye wash. * * * “Dimmit” says Ericsson, “Vy don’t nic^ures go through the card board?” “W'hen I was on the road,” said Knobloch, “we found it necessary to remove the card board.” ❖ * 5^ Bro. Barnett appeared on Market Street the first day of April with a new straw hat, but the rain sent him home in a hurry to exchange it for the old reliable felt. * * * Was it Will Rogers or Poe that said, “In the Spring a young man’s fancy turns to thoughts of love?” Brother John Ford, Jr., our Secre- tary, is showering attentions on a fair young lady. Hs * ^ Bro. Triplett has been working strenuously in the last year at the Fox Theatre and decided to take a week off to regain his health and strength. * * * Bro. Frank Seavier, president of Chapter 16, is continuing to improve. Although not fully himself as yet, he will doubtless be back to normal in the near future. T p. 3380 (A) 3050 3000 2915 2800 2790 2500 2220 2020 1850 1800 1700 1450 w >» 0$ 05 bo ;s '3 o 1350 1250 1000 500 450 372.2 144.3 130 Visible Spectrum Limit of perception of red to average eye Red Orange Yellow Green Peacock Blue Violet Limit of perception of violet to the average eye Extreme limit of acute vision Ultra-Violet Spectrum Flint glass ceases to transmit Harmful effects on living tissue begins Limit of solar spectrum found by Miethe and Lehman Light crown glass ceases to transmit Dangerous to the eyes. Abiotic effects in- crease rapidly from here with shorter waves O N o 3. S' CTQ ps 3 a. td ps 0 c^- (D s; 01 p^ H o e-t~ Ordinary clear quartz begins to absorb Miller’s photographic limit Stoke’s limit of phosphorescence Ozone producing power begins Shortest wave length transmitted by a mercury lamp of clear glass. Rock salt ceases to transmit Limit of transparency of crystal quartz 2 m.m. thick Ionizing of air begins Limit of transmission of superfine flourite Saunder’s limit in spectra of Calcium in (1914). Also Schuman derived from hydrogen spectrum. Observed in spectrum of helium at 2 to 3 m.m. pressure by Lyman in 1917 Observed by Richardson and Buzzone in spectrum of helium. Observed by Milliken in the spectra of alu- minum, magnesium and sodium (1921) Thirty-one 3 8 56.25(A) 28.125 14.06 Slightly Explored Region Explored by bureau of standards 1922 Characteristic properties of X-rays’ X-rays and Gamma Rays 12.35(A) Longest X-rays from zinc observed Freeman by 1.66 .976 .619 .614 .580 .488 .475 .445 .122 .114 .071 .02 and shorter X-rays from nickel X-rays from palladium X-rays from rhodium Shortest measured X-rays (1917) Gamma rays Below this are the newly discovered cos- mic rays, the shortest waves known APPROXIMATE SUMMARY Octaves Wave lengths used in radio 9 Hertzian (very short radio) 14 Infra red or dark heat waves 11 Visible light 1 Ultra violet 5 Long X-rays, X-rays and Gamma rays 11 Total 51 Explanation of Units of Length Involved 10 Angstrom (A) =1 m.mic’n=107c.m. 1000 Millimicrons =:1 micron=104c.m. 1000 Microns = 1 m.meter=101c.m. 10 Millimeters (m.m.)=l centimeter. 100 Centimeters (c.m.)=l meter. The above data on Ethereal Waves should be studied carefully by every \ projectionist . It will impart to you a thorough working knowledge of this important phase of your ivork. We do not often have the privilege of print- ing such a completely comprehensive study of any subject. We, therefore, urge you to take full advantage of its value. — Editor. T h i rty ■ t no o (Continued From Page 10) on the direct current coil of the re- actance dimmer. The output of the tube control set is varied by means of a third (226) tube. The control of this tube is accomplished by means of the potentiometer located on the stage or auditorium switchboard as described above. A 30-volt D. C. source of potential is impressed on the potentiometers. The sliding arm of these potentiometers is connected to the grid of the control tube for this circuit. Thus by varying the po- tential on the grid from 0 to 30 volts the output of the tube is varied from maximum to minimum, which in turn through the reactance dimmer changes the intensity of the lights from full brilliancy to blackout, or to any intermediate position the opera- tor desires. Due to the fact that this grid con- trol is purely a potential control and that no current is required for same, it is possible to use telephone type wiring for the connections between switchboard and tube control board, thus cutting down the installation cost of the same. Furthermore, due to this feature whereby no current is used in the control circuit it is pos- sible to obtain a pre-set dimming and also a proportional dimming by means of which combination of colors may be brought up from blackout to any desired intensity obtaining ap- proximately the same hue through- out. This process may, of course, be reversed. This was not possible with the old type of control due to the fact that intensities could not be pre-set and therefore could not be varied as a group. 1 i i The fellow who talked about the “silent night” lived before the age of the loud speaker. KAELIN ELECTRIC CO. Motor Specialists Motor Generator Sets for Eliminating "B” Battery Spare Generators on hand for Emergency Calls Guaranteed Repairing on Motors and Generators KAELIN ELECTRIC CO. Phone WEstmore 2510 211 Venice Boulevard Los Angeles, California From Theatre Managers Publication Maybe We' re Wrong'. What Do You Think? All late model standard projectors are either constructed specially for sound picture projection or are read- ily adapted to any make or model of sound apparatus, either for sound-on- disc or sound-on- film. The latter method, due to greater thickness and density of film requires the use of much more amperage at the arc and this factor has been met with lamps and lamphouses of greater illumina- tive output capacity. Also the use of the perforated sound screen has to a very great extent added to the neces- sity of greater illumination. Moving picture projectors are now construct- ed more accurately and sturdily than ever before due to the more exacting requirements of talking picture pro- jection and greater area of picture surfaces. We print this as an amusing angle only. It is a very natural mistake for a non-technical publication. — Editor. Thirty - three LOUDSPEAKER FOR WESTERN PROJECTIONISTS Sponsored by California Chapter No. 7, A. P. S. A. L. FEINSTEIN, Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Kindly enter the following subscriptions to the Loudspeaker at $1.00 a year. (This rate applies to 5 or more subscriptions) Name Address Town State Name Address Town - State Name Address Town State Name Address Town ... State Name Address Town State Enclosed please find $ for subscriptions The rate for individual subscribers is $1.50 a year, single copies 25c Changes of address must be in the fifteenth of the month previous to the date of publication of the issue on which the change becomes effective. BE SURE WE HAVE YOUR CORRECT ADDRESS. T hirty -j our g ,-,-r »~r-y.r.. , , , ...... .jjj) EDDIE HARRIS Asks — "Are YOU Interested In A WELDED Film Splice — or — Does JUST A PATCH ; Satisfy You?” Our Slogan: "The Splice is Stronger Than the Film Itself,” < is not merely a "catch- word” — It means that the break in the film is ACTUALLY welded as steel is welded — FOR PERMANENCY! We feel, at this time, that an analysis of the working of - ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT and the ! ordinary QUICK DRYING cements on the market, will clear up ; a mis-understanding as to the value of a quick drying cement and one of less volatility. ; To WELD a break you must FUSE and MELT the broken pieces ! into each other to become ONE. To PATCH a break you just ] use an adhesive to make TWO SURFACES stick to each other ; FOR THE TIME BEING — They will come apart — in the case of ] film, ether will do that. ; Ether being highly volatile, dries quick, hence can only get a 1 surface grip on the film and soon opens ! ; ODORLESS— FLAMEPROOF— 2 in 1 FILM CEMENT having ! low volatility evaporates slower BUT melts and fuses the broken ] film into a WHOLE. A Film Splice made with 2 in 1 will STICK IMMEDIATELY ] but WILL NOT stand an immediate PULLING TEST. ; MAKE YOUR SPLICE— REEL YOUR FILM IN CONFIDENCE— AND FORGET IT! It’s $1.25 a Pint Parcel Post Also Makers of Tru- vision Parts, Fire X Liquid, Lens Paste, Rust Remover, ' Gum Remover, Perfumes, Etc. 2 CEMENTS INCORPORATED INTO 1 FOR USE ON SAFETY AND ! REGULAR FILMS ! H ewes-Gotham Co. 520 W. 47th St. New York T hi rty-five Western Projectionists ! AH progressive projectionists, technicians, service men and engineers should be subscribers and readers of “PROJECTION ENGINEERING” The largest technical circulation of any motion picture publication TELL YOUR FELLOW CRAFTSMAN ABOUT THE GROUP SUBSCRIPTION RATE The subscription rate for individual subscribers is $2.00 a year or $3.00 for two years. The group rate of $1.00 is available to you when 4 or more subscriptions are sent in at one time. For Your Convenience BRYAN DAVIS PUBLISHING CO., Inc. 52 Vanderbilt Ave., New York City. Enter the following subscriptions to Projection Engineering at the Ifl.OO a year Group Rate. Name Address Town State * Classification Name Address Town State * Classification . Name Address Town State * Classification Name Address Town State * Classification Name Address Town State * Classification *Please classify subscriptions sent in as follows: M — Manufacturer E — Engineer P — Projectionist Including execu- tives, purchasing agents, plant su- T — Technician D — Dealer or Service perintend ent, Man foreman, etc. BRYAN-DAVIS PUBLISHING CO. 52 Vanderbilt Avenue, i i New York City LS-5 i Thirty - six ZENITH Portable Sound System PERFECT SOUND REPRODUCTION COMBINED WITH PORTABILITY A complete description of the Zenith Sound Equipment was con- tained in the March Issue of the Loudspeaker. De Luxe Model . . Weight, Including Cases, 400 lbs. Standard .... " " " 200 lbs. Write for further information Breck Photoplay Supply Co. 1909 So. Vermont Avenue Los Angeles THE T. E. S. PRECISION FILM MEASURING MACHINE The Companion Instrument to the Cue*Meter SPECIFICATIONS: Heavy cast iron base — will not move around while measuring film. Large 64-tooth sprocket — constructed of duralumin -direct connected to counter — - no gears. Sprocket supported on two bearings. Frame numbers engraved on edge of sprocket. Counter placed at thirty degree angle — easy to read. Base open under sprocket. When placed over light on work bench allows frame l.nes to be easily distinguished without removing film from sprocket. THEATRE ENGINEERING SERVICE CO., LTD. 1442 Beachwood Drive Hollywood, California For Sale by All Branches of the NATIONAL THEATRE SUPPLY CO. DON’T GU€SS ••• USE CUE-METERS LOUDSPEAKER FOR WESTERN PROJECTIONISTS At left, Brother Marvin H.Thoreau; at right, W. McMillan. Both are prominent A. P. S. men of Vancouver, B. C. Brother Thoreau is President of Chapter II of that city. Volume 2 Number 8 AUGUST, 1931 Price 25 Cents ► ► ► ► ► ► ► ► ► ► ► ► Complete Service ; for your : Projection Room ; or your : Theatre ► ► ► ► ► ► ► ► Intelligent, Concientious Co-operation National Theatre Supply Co. Executive Offices --92 -94 -96 Gold Street, New York Efficiency Due to careful design — the result of long experience. Freedom from necessity of replacement parts and Economy excessive maintenance costs. No condensers to break. Carbon consumption IS NOT excessive. THE ASHCRAFT AUTOMATIC ARC CO. 4214 Santa Monica Boulevard One & Protfjer Has <§one Chapter Seven is plunged into deepest sorrow. Brother Roy E. Clark has passed on. His genial personality and able craftmanship made him countless friends both in and out of the profes- sion. His passing casts a deep shadow of mourning over the chapter of which he was a member. Our brother is gone but the memory of his good works will live in our hearts forever I^Tech nical and Educational Publication. Devoted to the Western Projectionist and h is Progressive Fellow Craftsman Everywhere. RODNEY T. BACON W. G. CROWLEY H. E- ALFORD Supervising Editor Editor-in-chief Business Manager W. R. HERMANCE '264 Welton Way A. L. FEINSTEIN Staff Photographer Inglewood, Calif. Pleasant 7332 Circulation JAMES B. GILLARD, Oakland Editor FRANK W. COSTELLO, San Francisco Editor 1436 Delaware St. Berkeley, Calif. 1230 Hyde Street, San Francisco Technical Editors: A. C. SCHROEDER, D. B. McGOWN and R. H. McCULLOUGH Volume II. AUGUST, 1931 Number 8 CONJTENJTS Reorganization Movement Gaining Impetus ... 5 Academy Dinner at Paramount Studio 7 Photo Electric Cells By Richard Van Slyker . . 9 Bay Cities Chapters Pass Resolution 13 Anthony and Cleopatra — A Modern Version By Frank W. Costello, A. P. S 14 Dowser Switch Developed ‘ .... 16 Things in General By the Editor 17 Spasms By J. B. G 19 Secretarial Comments on Business and Pleasure 20 Health Talks for Projectionists 22 Electro Dynamic Transmitter By E. R. P. I. . . . 23 Pin Spots 24 Published Monthly, Sponsored by The California Chapter Number Seven, A. P. S. Subscription Price, $1.50 Per Year. Single Copies, 25c. Address Circulation Manager, 2432 Cloverdale Avenue, Los Angeles, California. Established 1930. Advertising Rates on Application. Address Advertising Manager, 2628 West Blvd., Los Angeles, California Three I. A. T. S. E. EMBLEMS 4 inches in diameter in blue and silver enamel with attachment for fastening to your radiator, and with the number of your own Local. Price $1.50. Ask your Local Secretary about them. CLYDE W. SHUEY, 51 Rose Avenue, Venice, Calif. Manufacturer and Distributor NEW ADDRESS J. SLIPPER & CO. LTD. 1968 SOUTH VERMONT AVENUE LOS ANGELES, CALIF. Theatre Equipment and Supplies Motion Picture Machines Douglas Sound-on-Film The old reliable supply company that guarantees everything they sell. <*7 our Reorganization Movement Gaining Impetus A. P. S. LEADERS FAVOR HOLLYWOOD Progress is being made in the right direction in spite of many misinter- pretations concerning the purposes of the impromptu committee that met in Hollywood to discuss ways and means of promoting academic and fraternal endeavor within the society. It was the intention of this group that represented five of the largest A. P. S. Chapters in existence to stir the long sleeping national organization into wakefulness. This attempt has not yet been wholly successful. There are however faint rumblings of the awakening giant. Crossing and re-crossing of opin- ions have proven a national interest in the movement. Thinking projec- tionists all over the country have ex- pressed themselves as being heartily in favor of reorganization. Many easterners have frankly stated that they believed that the headquarters of the society should be in the West. This is a very logical solution to the problem. Welman Favors Coast The following statement was made by Victor A. Welman of Cleveland, Ohio, Chapter 18, in a letter to The Loudspeaker. Bro. Welman said in part : “Secession is usually the first thing thought of in such situations, but time has proven that it should not be resorted to until all other possible remedies have been tried. There is no use trying to hide the fact that the A. P. S. as a whole is not functioning satisfactorily, and it is apparent that many members are disgruntled and ready to throw up the sponge. How- ever, I am confident that a good job of reorganization will answer the needs of the situation. I favor the headquarters being on the Coast; and I do not think the present national officers will oppose a reorganization.” Numerous other letters, each ex- pressing a very similar line of thought, have been received. Burton Interviewed Bro. Sidney Burton, who is presi- dent of California Chapter No. 7, A. P. S., was interviewed by The Loud- speaker in regard to the reorgani- zation movement and gave the follow- ing statement: “Chapter No. 7 has sought constantly since its organiza- tion three years ago to promote the interests of the American Projection Society in every way possible. Our scope was limited by two things, namely, lack of jurisdiction and lim- ited finances. The chapters organized by us in the West contributed nothing to our attempts to further the cause in other locations. These chapters sent their financial assistance to the Supreme Chapter in New York. The Supreme Chapter was content to de- vote these funds to some purpose other than assisting our Chapter or (to our knowledge) any other Chap- ter to promote academic or fraternal endeavor. It is my hope that in this reorganization a plan will be per- fected that will make possible an or- ganization campaign that will unite the entire projection craft on this continent into one organization devot- ed to academic and fraternal endea- vor. Bro. Seavier in starting this movement has, in my opinion, created the proper opening for just such an accomplishment.” Georgia Man Sends Views One of the outstanding figures of the projection craft in the South who has been in close communication with this paper for many months is Bro. P. Dozier Colson of Clayton, Georgia. fyi Mr. B. P. Schulberg and the officers of the Academy were hosts to a din- ner in Paramount’s studio dining room Wednesday night, May 6th. Over a hundred invitees, prospective members of the Academy, were pres- ent and in addition the members of all the branch executive committees of the Academy. President Wm. C. deMille of the Academy presided. Mr. deMille said : “History is repeating itself tonight. Four years ago this month a similar group of noted men and women chos- en from the five major branches of motion picture production met to found the Academy of Motion Picture Arts and Sciences. Douglas Fair- banks became our first president. “In four years the Academy has grown to be the ‘house of representa- tives’ of the motion picture industry. Six hundred members — actors, writ- ers, directors, technicians and pro- ducers— are now banded together in an established program of concilia- tion, artistic and technical develop- ment and in creating good will and understanding between the public which sees and hears us and ourselves who entertain them. “Among the significant accomplish- ments of the Academy have been the adoption of the basic agreement be- tween the actors and the producers, the arbitration of many cases requir- ing adjustment, the solution of tech- nical problems common to all studios when sound came in, the initiation of courses in the cultural appreciation of our art in colleges and universities, the publishing of bulletins, reports and books as aids to artist, the pro- ducer and the technician ; the circula- tion of information to the thousands of inquirers who address our office from all over the world, the enter- tainment of distinguished visitors to Hollywood. Notable among the lat- ter were dinners the Academy gave to visiting British journalists and to a delegation of foreign journalists rep- resenting seventeen different nations. Not the least of our activities has taken the form of numerous addresses by our members and by our staff throughout the United States inter- preting the ideals of the Academy and of modern motion picture production to clubs, conventions and educational institutions. Some call this ‘public relations,’ which, after all, is a proper term, for the 100,000,000 Americans who witness our shadows work on the screen are indeed our public relatives who have adopted us into their homes and their lives. Not a little of the good cheer required in these days has been supplied by those who make pos- sible the motion picture and its power to make the individual forget the cares, the worries and the discour- agements of the day. Those who do not know us are those who misunder- stand us. The cardinal principle of the Academy is therefore conciliation, whether between branches, between individuals or between us all and the public. The Board of Directors has author- ized me to say tonight that by their unanimous vote the dues of Academy members have been reduced from $60 to $30 a year immediately effective and that the initiation fee formerly $100 will in the future be $25. This action represents the Board’s faith in our rapidly growing democracy, electing annually a Board of Direc- tors with three representatives from each branch. The reduction in dues is made possible through our growth over four years and evidences the Academy’s desir.e to make it possible for every invitee to join our ranks. With the exception of the Assistant Directors’ Section of the Academy the Board has voted not to elect further associate members and has asked me to express the hope that the reduction Seven in the dues of Academy members will cause most of our present associate members to request transfer to the full privileges of Academy member- ship. A review of Academy functions would be incomplete without remind- ing you of the national and interna- tional interest that has been aroused by the bestowal of the annual Aca- demy award in the form of the gold statuette of merit. Ten awards will be voted by the Academy member- ship this fall, registering the judg- ment of the crafts upon the distin- guished work of individual members of our profession. These awards are a coveted emblem of personal achieve- ment, the highest honor the industry can pay a member. Mr. Louis B. Mayer, chairman of the Awards Com- mittee, has in process plans whereby the annual awards dinner of the Academy, to be held the first week in November, will bring together in Hol- lywood the notables of the industry from all parts of the United States. This event promises to be the great- est in size and in importance in the thirty years of the history of motion picture making. It is to such an institution that the Board of Directors have invited you to membership. The Academy needs you and you need the collective spirit and benefits of the Academy. Scores of our members serving on Academy boards and committees can testify to the pleasure they derive from this fellowship of service which has be- come an integral and vital part of this great business.” Mr. deMille introduced the follow- ing who spoke of the branch activities of the Academy: Conrad Nagel and Sam Hardy, who spoke for the act- ors; A1 Cohn and Waldemar Young for the writers, Frank Lloyd for the directors, Col. Nugent H. Slaughter and J. T. Reed for the technicians and M. C. Levee for the producers. Mr. B. P. Schulberg, chief executive of Paramount’s West Coast studio as part host of the dinner, presented a picture program in the theatre of the Eight studio following the dinner which was attended by 150 members and invitees to membership. i 1 i Little Willies' Definitions Water is composed of two gins — Oxygin and Hydrogin. Oxygin is pure gin, Hydrogin is gin and water. A magnet is a thing that you find in a bad apple. The tides are a fight between the earth and the moon. All water tends towards the moon because there is no water on the moon and nature ab- hors a vacuum. Gravitation at the earth keeps the water rising all the way to the moon. I forget where the sun joins in this fight. Three states of water are high wa- ter, low water and breakwater. i i i USE OF RESISTORS IN AT- TENUATION DEVICES Attenuators or ‘pads” as they are sometimes called, are employed for the purpose of introducing into the amplifying system a definite amount of loss. Such devices consist essen- tially of a network of series and shunt resistors whose values determine the amount of loss introduced. Accuracy of the resistor units is absolutely es- sential if the calibration of the at- tenuator is to be reliable, and per- manence of value of these resistors is essential if the attenuator is to main- tain this calibration. Since these at- tenuation devices are employed in au- dio frequency work, the calibration must be accurate over wide bands of frequencies. Therefore, the resistors must be free of inductance and ca- pacity effects. Confronted with such rigid speci- fications, the engineers of the Inter- national Resistance Company set to work some time ago developing spe- cial units to meet the requirements. — Reprinted from Projection Engi- neering. Photo Electric Cells By Richard Van Slyker The surprising growth in recent years of photo-electric cells (photo- tubes), as applied in the industrial field may be easily understood when the versatility of the photo-tube is known, when seen in the countless uses to which it has been applied. A review of its multifold uses show that it ranges from automatic counting and sorting of various sized objects to the most delicate comparisons of colors and measurements of densities and of semi-transparent objects with an almost unbelievable degree of ac- curacy and fidelity. As mentioned in a previous chap- ter, photo-tubes when used in an am- plifying circuit require two types of amplifiers, the static and dynamic. Where we deal with slow gradual or abrupt changes of light intensity the static type of amplifier is desirable in one or more modified forms be- cause of its easily controlled range of action and simplicity of construction. However, in some cases it is desirable to incorporate in the amplifier design an oscillating circuit so as smaller light intensities of a pulsating nature may be handled with a greater de- gree of sensitivity. This addition of an oscillating circuit permits a con- ventional design of dynamic ampli- fier to be used in gaining additional volume. Again in the classification of photo- tubes the uses of the photo-tube is divided into several classifications ir- respective of whether the tube is pho- to-electric, actino, or photo voltic. A LIGHT SOURCE B LENS C SUBJECT D PHOTO CELL E LIGHT RAY The divisions are: (A) — Where the subject is inter- posed between the light rays and the photo-tube. (Fig. 1). (B) — Where the reflected rays of the subject are directed to the photo- tube (Fig. 2) . (C) — Where the measurement of light intensity is such as to permit direct exposure to the photo-tube (Fig. 3). It is the intention of this article to try and present to the projectionists some representative uses of the pho- to-tube as shown in the above classi- fications, outside of the immediate use of the motion picture industry. In the accompanying photograph (Fig. 4) a means of automatic con- trol of the mixing, or, titration of Nine FIG. 1 chemical mixtures is shown. The manner in which this sys- tem operates is as follows : In reverting to the first classifi- cation of photo-tube uses (A) in which the light ray pene- trates the subject. We have in this system the light source (A) which directs the light ray through the liquid solu- tion (B) which upon increas- ing in density due to the addi- tion of chemicals, permits less light to pass to photo-tube (C) that due to its directly proportionate output causes a correspondingly less current to flow to amplifier (D) which in turn permits relay (E) to work, passing power to valve (F) stopping the flow of che- micals to the beaker. This is representative of the daily use in chemical and pharmati- cal laboratories of the photo- tube. In the next example which is representative of classifica- tion (B) we have a circuit shown in Fig. 5 where a re- flecting mirror is used to di- rect more or less light to the photo- tube. In this particular case a thermo- couple is suspended in a hot bath or place where the accurate control of heat is necessitated to a microscopi- cally small degree as in retorts, blast furnaces, plating baths, etc. The output of the thermo-couple is con- nected to a sensitive galvanometer which carries a small reflecting mir- ror (M). The light ray (L2) is then directed to the stationary mirror (Ml) thence, to photo-tube. From the photo-tube the current goes to the amplifier circuit shown, and then to relay (R) from the relay the control- ling current permits the addition of more or less heat to the subject under control. The light source (L) is con- centrated by lens (LI) upon the gal- vanometer mirror. Other uses of the reflecting system with the same circuit, with the ex- ception of the galvanometer is that of grading and sorting of various ob- Figure 4 jects and color comparison by placing the subject to be scanned. Where the rays from the light source reflect from the subject to the photo-tube, the relay either stops the operation of the machinery or sounds a warn- ing, notifying the attendant in charge that something is amiss. In this man- ner exceedingly accurate comparisons of various subjects may be had. In the last classification (C) where the direct light rays from a source are permitted to impinge upon a pho- to-tube, we have a means of measur- ing light intensity and (depending upon the photo-tube composition) the various light spectrum that are pres- ent. In this manner some of the main uses are in stella photometry, light photometery and spectral photome- tery. One of the latest uses is that of an exposure meter mounted in a cam- era to give an instantaneous means of measuring the intensity of illumi- nation on the set as picked up in the Ten camera. In stella photometry the photo-tube is accurate in the measure- ment of distant stars brilliancies. In lamp photometry it gives a nearly in- stantaneous means of measuring light brilliancies of a room or a mov- ing picture screen, or of a light source. In some cases the use of color filters, which are composed of spe- cially tinted glasses, is an advantage to eliminate undesirable light rays, which if permitted to remain would confuse the issue. In again reverting to the first clas- sification (A) in which the light ray passes through the subject, we have in a special case where a means of density control is necessitated by a photo-tube. A photo-tube of a spe- cial nature is required, this photo- tube was evolved because of the ne- cessity for a tube of linear or straight line characteristics and stability which was unattainable in the pres- ent day form of manufactured tube. The sensitive area in this type of tube is composed of (if I remember correctly) nickel-chrome wire coiled in a form of a cone (Fig. 6). Two such cones being joined at their apexes, a small voltage is then ap- plied which causes them to glow faintly (about a dull red) . This tube is one of the “actino” family, as it is resistive in action. At the moment this tube is being used in reclamation of silver from “hypo” in a large film laboratory. At a particular point in the equipment used for reclamation, a photo-tube is needed to determine the specific density of the hypo-solu- tion within extremely narrow limits of “density,” which necessitates a photo-tube of these characteristics. The use of photo-tube in the read- ing of light vibrations or fluctuations in conjunction with an oscilliscope, gives an accurate means of studying the wave form of any unknown light source of either near or distant ori- gin. A photo-tube, when used in con- junction with an oscilliscope, is con- nected in such a manner as to pick CIRCUIT CONTROLLING GALVANOMETER FIG. 5 E le