Excerpt from Text-Book on Wireless Telegraphy, Vol. 2 of 2: New Edition in Two Volumes, With Illustrations, 8vo;, Volume 1. General Theory and Practice, Volume II. Valves, Continuous Waves and Radio-Telephony During 'the last four years the apparatus and practice of radio signalling have been revolutionised by the rapid evolution of the hard vacuum valve 'and of valve circuits. This new era may be said to have commenced with the results obtained by Dr. Irving Langmuir, the explanation of which was clearly set forth by him, and by Edwin Armstrong, early in 1915 before the Institute Of Radio Engineers. The great world war was responsible for some remarkable developments in applied science. Not the least of these was the impetus given to radio signalling, by its multifarious applications in all branches of war activity, both offensive and defensive. 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.