Moving Picture World (Jul-Sep 1912)

46 THE MOVING PICTURE WORLD the lamp is not made for 60 amperes. Am I right? I run over my films every morning, cut out the bad places, cement the loose patches; also notch torn sprocket holes. Therefore I seldom have a stop. One of the machines has a grind in it. It isn't much. I think the toggle gear is worn out. Am I right? If that isn't the trouble, please tell me what it is." Glad to hear from you Anniston, and to know that projection is on such a high plane in your city. We have had quite a number of letters from Alabama, in the past, particularly from Atlanta. As to the grind in your machine, you say you have two Edison machines, and then speak of the "toggle gear," which is a Powers gear. The Edison has no gear called a toggle gear, nor any corresponding to it. therefore I guess you will have to explain a little more clearly. If you have a Powers machine, then get a copy of the January 6th issue of The Moving Picture World. If you have an Edison machine, get a copy of the June 1st issue of the World, in which appear respectively photographic instructions on the Powers 6 and the Edison Model B machines, the same being a part of the new edition of the Handbook, which will be out about September 1st. I think these instructions will enable you to locate your trouble. If by a "two-way switch" you mean that your machine lamps are both connected to one double-throw switch, I must advise you to make a change there. That is not the best practice. See page 58 of Handbook. I think your manager would find an intermission of 30 seconds between each picture to be good practice. Running one picture after the other without any stop at all is being discarded by many managers. See top first column page 1130, June 22 issue. As to the carbons misbehaving when sixty amperes are used, I am inclined to believe one of two things, viz.: Either your compensarc is delivering in excess of 60 amperes — a matter easily proven out by having your light company test out your secondary output with their ammeter — or that the carbons flame more when treated with salt brine and subjected to their capacity amperage (a Yt, cored carbon is at its capacity, or about so, with 45 amperes D. C, or 60 amperes A. C). In fact, unless I be in error it has been reported that there is a greater tendency to flaming when the salt brine is used. The lamp being not made for 60 amperes would simply operate to cause excessive resistance and reduce the amperage. However, the fact that the carbons get red hot half way up makes me conclude that they are working above capacity; therefore test out the amperage delivery. LONGER THROW. — Iowa (name of town suppressed) writes: "Am remodeling my theater and expect to have a longer throw. What size lens should I use for a 90-foot throw and what size curtain must there be? Expect to put my curtain on the wall, can you suggest a good wall coating? Am still having trouble with my intermittent sprocket. My pictures shake a good deal. Am using a Pathe machine. The intermittent wheel is loose. Do you think a new intermittent or cam wheel would remedy matters?" Your information, Iowa, is rather indefinite. I cannot tell you the necessary focal length of lens without knowing the exact distance and width of picture. Even then, I would have to know the exact width of aperture. Proceed as follows: Measure the distance from lens to screen; measure the exact width of the aperture of your machine, using a pair of inside calipers and a finely graduated machinist scale, so as to get the exact measurement. In measuring the distance the calipers are open, you can use a condenser for a magnifying glass. Now multiply the distance from screen to lens; in feet, by the exact width of the aperture in fractions of an inch. Multiply this result by 12 to reduce it to inches, and divide it by the exact width of the picture you wish to have in inches. The result will be the equivalent focal length of the required moving picture lens, as nearly as it is possible to figure. For example, suppose you want a 10-foot picture at 64 feet; machine aperture 15-16 of an inch. 64 X 15-16 = 60 X 12 = 720. 10 X 12 = 120. 720 -£■ 120 — 6 = EF of required lena. Exact results, however, cannot be expected, for the reason that there is considerable variation in cheap lenses; also it is not always possible to procure exactly the required focal length of lens. You say you will place your screen on the wall. By this, I presume you mean that you will frame a part of the plaster wall as the screen. If so, then white muralite or alabastine is a good coating (to be had of any dealer in painters' supplies), as is also English whiting, which can, I believe, be secured of any druggist, but which must be mixed, using a little glue and a little ultramarine blue. The wall can also be coated with white lead mixed half oil and half turpentine, adding enough ultramarine blue, ground in oil, to give it a decided blue tint when in the pot. This will mean that it will be pure white when en the wall. You say the "intermittent wheel" is loose. What do you mean by that? There is an intermittent sprocket and star on the intermittent shaft, both of which must be secured rigidly to the same. If they are loose, then either they must be made tight, or you must procure a new part. I would suggest that you order a new intermittent shaft, star and sprocket assembled, and put it in place of the old one. Your screen may be any size from 12 to 18 feet wide, but with a 90-foot house I would suggest 15 or 16 feet. VARIOUS THINGS. — California writes: "I notice in the issue of June 8 an argument about the six months' apprenticeship law. I will set forth what I ran up against in San Francisco about a year and' a half ago. Being out of work at the time, I went out to where the operators' headquarters were and had a very short talk with a genial, pleasant faced young man who occupied the other side of the railing, about the prospects of joining the local union. The question of residence came up and was disposed of. A few other questions followed, and along with them came the six months' apprenticeship law. When I came to that I objected on the grounds of having previous experience. No, I must serve six months as an apprentice before being allowed to have a card as a journeyman. I say that the law is wrong in all senses of the word. If any one, having previous experience, can take their examination and pass, is there any reason why he could not be admitted to the local as a journeyman operator? A six months' apprenticeship does one but very little good. In the Electrical Workers' Union, an apprentice must serve three years, or until qualified to pass the required examination. If he fails to pass, he must keep on serving until he can. That, it seems to me, is the way it should be. How much good can any apprentice derive in that short space of time, and how much can he learn in that time? Very little. I have been in and cround the business for the last ten years and don't begin to know as much as I ought to about it. I never expect to know it all. The local residence law is another poppycock proposition. Will someone kindly set forth a good and sufficient reason why a chap must live in a town or city six months before he can get a job? Bosh! Or, as you say, 'Piffle.' Let the coming convention pass a law requiring all apprentices to serve at the very least two years before they can become journeymen operators. Also, that if a man, by diligent study and hard work, can qualify himself and bring himself up to the best standard he can be granted a journeyman's card, even before he has served two full years. That is, if he can pass a very rigid examination. Also an age limit should be set whereby irresponsible boys can be prevented from handling a picture machine alone. I have seen numerous cases where small boys were employed because they could be had for half, or even a third less wages than a good, competent operator could be had for. This is all wrong and all operators of worth and ability should fight hard to suppress the 'kids.' Think I have had my little say, so will close, wishing you and the World all the success you both deserve." 1 do not think I shall comment on this letter. I have .printed it practically as written, for I believe these matters should have full and free discussion. I am a great believer in bringing things out into the open, and examining them, lop, bottom and sides. It is thus the truth is arrived at, and just conclusions reached. It' the six months law is wrong, then the opinion of those opposed to it will, in the end, prevail. If it is right, then the said opinions should not and will not prevail. At any rate, let us discuss ■ these various matters openly, but without rancor, or ill-feeling. The brother sends in a sketch of, what I presume to be, his operating room. It contains two machines, spot light, a working bench, switchboard, rewinding tables, and supply cabinet. The room is 8x11x8 feet high and is very well arranged. CATALOG WANTED. — Newport, Ky., wants to know where he can secure the latest Lubin catalog. Write the Lubin Company, film manufacturers, Philadelphia, Pa. VARIOUS COMMENTS.— Mr. P. E. Chapman, electrical engineer, St. Louis, Mo., contributes the following: "The writer, who reads this department with extreme interest, being an amateur moving picture man, notes the trouble of the brother from Edinberg, Ind., and the diagram accompanying same in issue of June 15. If a professional electrical man be allowed to butt in he would say that the diagram submitted is absolutely correct, and that the light will work as intended if his wiring is according to diagram. However, the gentleman's wiring, with all due respect to his opinions to the contrary, is not according to the diagram. What he has is the piano light wire (which is shown attached to the top house-light wire in the diagram), attached to the lower wire, if he will reverse it — that is disconnect and connect to the opposite wire he will find his trouble will cease. See sketch attached herewith. The piano lamp burns when double pole switch is open in series with the house lights, as1 he had it, they are so low resistance especially if tungstens, as to dim the piano light imperceptibly. On page 5 of the Handbook, and several other places the writer has noted statements that if one ampere at 2,000 volts should be transformed to no volts the current would be about 10 amperes. I believe this is an error that escaped your notice in proof reading, as the products in volts and amperes of a primary and secondary must be equal, always of course minus the small losses of transformation, this would make 18.2 amperes, or about iS amperes, allowing for slight loss. This statement should either read, according to current practice, "i ampere at 1,100 volts transformed to no volts would be approximately 10 amperes;' or, '1 ampere at 2,200 volts transformed to no volts would be approximately 20 amperes.' In the same issue 'Salt Brine,' from Indiana, wishes to know what the effect of running 60 amperes through his 40 ampere meter would be. Would beg to say that if he is using, as you suggest, 60 amperes with a rheostat, that, contrary to opinion expressed, that the meter would not register this current, the meter will register this current, and not only will it register it, but what is still worse, if it is run as indicated for more than a few minutes it will be very likely not ©nly to register the current, but to speed up, and register fast on all loads, for nearly all recording watt meters used in this country measure by loading down the moving element with magnets working through a disk which is practically a short circuited dynamo. If this disk is run beyond a certain speed it will generate sufficient current therein to demagnetize these mag