Page:Popular Science Monthly Volume 91.djvu/615

 Making It Easy to See the "Movies

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��How tedious inserts can be avoided and how the clock can be watched

THANKS to the invention of Dr. J. W. Billings, any explanation that needs to be made in a motion-picture can appear at the same time that the action is going on. The inventor calls his contrivance for projecting captions a "descriptograph." In general appearance it looks not unlike an ordinary stereopticon. In the place where lantern slides ordinarily go, however, is a large disk having a number of radial openings. These radial openings contain the captions to be thrown on the screen and go through the field of the lenses on the lantern one after another, being moved along by an electromagnet, one radial open- ing at a time. On the film are little metal rivets or eyelets. When the film slides through the guiding and feed ' rollers, there metal rivets make an electrical contact with the rollers, completing a circuit through the electromagnet on the auxiliary lantern, or "descripto- graph," down in the orchestra pit. This causes the descripto- graph to throw a fresh caption on the screen. Just before the ac- tion on the main film is to change again, another rivet appears on the film, makes proper contact, and causes the electromagnet to

�����The disk which contains the captions printed for the screen in radial openings

��Clock mechanism

Drive qear Revolvinq di*'* A machine for projecting both advertise- ments and a clock-face to tell the time of day

pull a new caption into place. The whole plan is here illustrated. Another device somewhat like the descriptograph is also being marketed. This contrivance, however, is for the purpose of projecting advertisements in- stead of captions. It has a special screen of its own, much smaller and to one side of the main screen as is shown in tie il- lustration. In conjunction with its advertisement-showing fea- tures, this machine also projects the hands of a clock and a clock dial at the same time, this latter feature being an integral part of the advertisement. Since people attend- ing the show will inevitably look at the clock now and then to keep track of the time, the clock serves the special purpose of attracting attention to the advertisements. As is shown in the illustration, the clock hands project inward from the rims of two large and hubless gearwheels through which light from the lenses of the lantern passes. In practically the same focal plane as that of the hands a wheel revolves in which are some half-dozen regularly spaced openings about the size of a quarter. Transparent celluloid disks cover these small opening: , and on these the advertisements are painted or printed. By means of a suitable escape- ment device, this wheel shows six adver- tisements in rotation.

��brass eyelet

the space left

the caption

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