Excerpt from Journal of the Society of Motion Picture Engineers, Vol. 19: July, 1932 Summary. - One hundred and thirty types of picture projection lamps are today required to fill the demands placed on the lamp manufacturers. This large number of types, each being available in several different voltages and in most cases with either one of two kinds of bases, brings the total to over 500. The total annual demand for the entire country is only units for lamps of this type. The result is that the lamps are expensive and that the amount of engineering that can be devoted to each type is entirely inadequate. This situation is partly because small improvements in lamps have been made almost annually in the past, and partly because of wide diversity of opinion among projector designers. By assembling and coordinating the ideas of equipment de signers, an ideal set of light source requirements can be laid down. Based on these requirements the lamp manufacturers can then establish the characteristics of light sources to be introduced during the next few years. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.