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projector so that perfectly steady control could be obtained when there were no standards to follow.
There seemed to be an endless variety of perforation gauges. Even the product of any certain maker of motion pictures showed a wide variation in distances between all centers, absolute uncertainty of spacing, and perforations of many varying forms.
Even one certain film subject would have all of the above characteristics. This made it necessary for all sprocket teeth to be machined so small that film of any or all variations would pass through the machine without damage.
As it was not practical to machine sprocket teeth or other means of control to closely lit into the sprocket holes of the film, it was found necessary to provide an extreme tension so that when the film came to the period of rest, it would remain in a fixed position, and on account of the variation of the position of the dividing line, it was necessary to provide means to bring the film in registration with the aperture as the various sections of the film came into position for projection. This means of adjustment was also necessary because the extreme tension on the film over the aperture caused a strain against the walls of the holes sufiicient to cause tears, and a poorly made splice would often cause the film to leave the sprocket, which necessitated framing pictures many times during an exhibition.
These conditions still prevail, but I am happy to say in a far lesser degree than that of a few years ago.
There still is, however, a considerable variation in the products of various manufacturers, and I firmly believe that the first step toward standardization must be to establish what shall be the size and form and spacing of perforation.
In justice to the manufacturers of projecting apparatus, I must say that they now have provided a fixed standard, this being the diameter of the Intermittent Sprocket. Investigation shows this standard to be 15/16ths of an inch, and as this diameter appears to be in general use, it is well that this may be considered as a standard established and to be followed.
This standard gives a working basis on which we may determine what must be the distance between the centers of the perforations, both lineally and transversely, but before fixing these standard dimensions, we must consider the normal amount of shrinkage of film after development. We must consult the Laboratory Superintendents, and make thorough scientific tests to establish the normal amount of shrinkage of both length and width of film after being developed and dried. We then may establish standard lineal and transverse dimensions between centers.
The manufacturers of projectors do not appear to have established a standard distance between each series of sprocket teeth, but I believe they must look to the motion picture manufacturers to adopt a standard of perforation, so that they may have a guide