Living pictures; their history, photoproduction and practical working. With a digest of British patents and annotated bibliography (1899)

Page scan 000147 from Living pictures; their history, photoproduction and practical working. With a digest of British patents and annotated bibliography

Record Details:

Title:
Living pictures; their history, photoproduction and practical working. With a digest of British patents and annotated bibliography
Date:
1899
Publisher:
London Optician & Photographic Trades Review
Volume:
Living pictures; their history, photoproduction and practical working. With a digest of British patents and annotated bibliography
Leaf #:
000147
Language:
English
Collection:
Books
Format:
Books
Contributor:
Robarts - University of Toronto
Sponsor:
University of Toronto
Coordinator:
Media History Digital Library
Description:
52
Date Added:
July 19, 2022
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PRESENT-DAY APPARATUS. 121> continually pulling at the film, and at the end of an exposure the film lies in a straight line between them and the pressure-frame. An interposed disc bears an eccentric rod, which strikes the film once in a revolution and draws some film down. It will be seen that for a fixed position of the disc the amount of film drawn on will depend on the distance over which the dog travels in contact with the film, and this is adjustable by shifting the dog along a slot on the disc. On the other hand, the relation between the periods during which the film is moving and stationary is governed \:iy the number of degrees (i.e. the propor- tion of a revolution) during which the dog touches the film. If, therefore, the disc be made larger and its centre removed to a greater distance from the film, the dog will bring down an equal quantity of film in a less time, leaving the film stationary for a longer period. Fig. 143. D2. Film moved intermittently by reciprocated roller, etc. The roller which strikes the film need not have a rotary action, though that is perhaps the best form, there being no dead point. Evans in 1890 showed a double tilting-arm applied to this purpose (see Figs. 71 and 72), while Varley almost simultaneously invented a cam-reciprocated arm (Fig. 73). Both these actions took place over an arc ; but Fig. 144 shows a crank-rod driving a roller in a line at right angles in order to loop the film. Blair has suggested a machine having a rise- and-fall shutter instead of one according to the ordinary type; and his drawings show the roller placed on top of K