Excerpt from Light, Photometry and Illumination: A Thoroughly Revised Edition of "Electrical Illuminating Engineering" This book is designed as a text in illuminating engineering and a reference for the practicing engineer. It is the outgrowth of sets of notes written and compiled by the author for use in his classes at the Armour Institute of Technology, and of his previous book, "Electrical Illuminating Engineering." In the construction of this volume the author has freely consulted the volumes of the technical press and particularly the Transactions of the Illuminating Engineering Society, the Illuminating Engineer the Bulletin of the Bureau of Standards, and the Electrical World. It has been the aim of the writer to assemble the best ideas and thoughts available on the subject of artificial illumination and in so doing he has freely drawn from the works of eminent authorities on particular phases of this subject as will be seen from the references cited. In this connection grateful acknowledgment is made to the writings and investigations of Dr. H. E. Ives, Dr. A. S. McAllister, Dr. E. B. Rosa, Mr. M. D. Cooper, Mr. A. J. Sweet, Mr. A. A. Wohlauer and others whose excellent papers and kind permission to use them are greatly appreciated. The author also washes to express his appreciation of criticisms and suggestions by Dr. H. E. Ives, of the kindness of Mr. F. H. Bernhard in reading proof and criticising copy, and of the efforts of the publishers in editing the book. 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.