Excerpt from On the Theory of the Matthews and the Russell-Leonard Photometers for the Measurement of Mean Spherical and Mean Hemispherical Intensities We shall now pass on to a m01e complete discussmn of the problem of the number of mirrors and their positions on the arc, . With par ticular reference rather to the integrating photometer for incandescent lamps than to the instrument intended especially for are lamps since, as stated above, it was in connection with the design of an instrument of the former type for the Bureau of Standards that these computa tions were made. 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.