The optical system is to be of the best. A picture smaller than a postage stamp is magnified to the width of twelve or fifteen feet and the lens maker has to exercise his best skill to secure a flat image with no trace of aberration. The intermittant movement has to be as precise as the mechanism of the dividing engine. When the Swiss watch makers developed the stop-movement to protect the mainsprings of their watches, they could not foresee the role it was to play. For on it depends the production of moving pictures all over the habitable world.
Electricity appears also in the work.
The operator no longer has to turn the wearying crank for hours at a time. Electricity does it for him. The projection of motion pictures is a process involving the perfection of mechanics, of optics, and of electricity.