Moving Picture World (Oct-Dec 1911)

286 THE MOVING PICTURE WORLD in different places under all kinds of conditicjns; several of my friends are using same, and I have yet to hear of a single condenser breakage. I open my doors any time I please and pay no attention to drafts. There is never a sign of trouble. "Believing that this will be of value to many operators, I am sending it in. Went to some expense for photos, but believe 1 am helping quite a few by so doing." The photos are worthy of more than passing notice. Unless I be mistaken, the pipe vent in top of lamphouse was our own idea, set forth in the Department a year or more ago It is most excellent indeed, but the pipe should be earned to connect with operating room vent flue or through wall to open air. A swing joint could easily be arranged so lamphouse could be moved over to stereo. This suggestion is not offered with any idea that there is danger of fire. There is none. However, city inspectors would not stand for it as you have yours, particularly with back out of lamphouse too. .\s to the motor drive, I don't think I would like the motor placed as you have it. It would create some vibration in table and be very much in the way. I think you will improve matters in this respect by studying some of the other drives now being published. In photo No. I it will be noted that a cone comes out from wall to meet the lens. Under certain circumstances this would be a most excellent arrangement and it is not bad under any circumstances. The lamp-lead conduits, as we see, pass from the cutout cabinet to the machine under the floor, which is altogether to be commended. The file for programs, etc., looks like the Princess had a real operator in charge instead of the throw-it-around-anywhere, Sloppy Ann sort we all too often find. What is it you have in the lower right-hand corner of the cutout cabinet? It doesn't seem to be an ammeter or voltmeter. Is it a meter? The connections, so far as I could trace them, make it appear to be the latter. That film cabinet (I'ig. 2) is excellent, particularly the sponge compartment. I don't like its location, however. You are in error there. As placed, it is more convenient, true, but near the floor is cooler, therefore better for the films. That machine stand looks to me as though it would not be very solid. An absolutely solid, steady stand is essential to excellence in curtain results. What is the box for at the back end of machine stand? Carbons? Tools? Now LaPorte, don't feel hurt or offended at these criticisms. You have a really excellent room and things are well arranged. However, still further imprvements, as outlined, are possible. Resistance? — Madison, S. Dak., writes: "Am installing my own electric plant in my theater. Kindly advise me as to whether or not I will need a rheostat in series with my arc. The current will be D. C. Have heretofore used A. C. from city mains and have, of course, used rheostat. With my own power, however, don't think I need one." Inasmuch as you have given no information as to capacity, voltage or kind of dynamo you have purchased, I am unable to offer you much advice. Your electrical knowledge is evidently somewhat limited. I would, therefore, I think, advise you to follow the ordinary procedure and use a rheostat. It seems to be possible to run without one with outfits constructed especially for that kind of service. Probably yours is not, however. If your dynamo is of the iio-volt type you will have to use a rheostat; in fact, a rheostat will be necessary with the ordinary dynamo, I hold, whatever its voltage; presuming you have no other arrangement for taking care of the pressure. Lens Focus. — Ashland, 111., writes: "Enclosed find $1.50 for handbook. What size and kind of M. P. lens is required to throw 12-foot picture at 80 feet. What kind of condensers ought to go with it. Powers Five machine and General Electric Compensarc. How much amperage for 80-foot throw, no v., 133 cycle? Seating capacity 450. Population 1.200. Some house." Turn to page 68 of handbook and figure out lens EF for yourself. Use an ordinary projection lens, any good make. Use two 75^ condensers. Length of throw has little or nothing to do with amperage. Amount of surface illuminated (size of picture) governs that. Forty amperes of 133-cycle current ought to give you an excellent picture. Even less may serve, as 133-cycle is the best A. C. we have for projection. Yes, that is a large house, indeed, for a town of that size. I note, however, it is a roller skating rink also. Machine Trouble. — Savanna. HI., writes, saying he has just installed a Powers Six and that everything went fine for a week. Then a ghost appeared. Also has trouble losing lower loop. Can make ghost smaller by moving lamphouse further back. Throw, 45 feet; 6^ condensers. The looptrouble does not occur on all films. You haven't told me width of picture, therefore cannot say as to what focal length condensers you should have. Probably, however, your 6]4 lenses are O. K. But are you sure they are that focal length? If you have a handbook, see p. 67. As to the loop trouble: disregard back roller and set front one so it clears sprocket by about tw-o thicknesses of film. When the bracket is closed down, see that the spring holding it only touches the lower point of the casting (see p. 887, Sept. 23 issue). If it touches the bracket casting elsewhere, when same is closed down, bend it (the spring) so it won't. Be sure the collars at end of rollers are set up so as to hold rollers in place sidewise, so that grooves in rollers are central with sprocket teeth. Don't get them so tight the rollers won't turn, however. Fuses. — The following is propounded by New York City: (a) Uses Edison machine, 25-ampere rheostat, no-volt current; has 30-ampere fuses on operating room and 50-ampere fuses about 10 feet from light company's fuses. When there is short or any trouble the light company's 70-ampere fuses let go instead of the others, (b) What advantage is there in one 6;/2 and one 7JX condenser lens? Would not both same focal length be better? (c) A brother operator claims a fuse will carry any voltage without being tested for same. I claim they are made to carry limited amount of voltage same as amperage, (d) Use Electra carbons. When bottom carbon burns down to about two inches sparks shoot from