Excerpt from The Telegraph Manual: A Complete History and Description of the Semaphoric, Electric and Magnetic Telegraphs of Europe, Asia, Africa, and America, Ancient and ModernIN the preparation of this volume, the author has not advanced theories, other than those which are founded upon demonstrated philosophy. It is to be understood, however, that many of the views expressed concerning questions in the sciences may, from time to time, be modified by new develop ments. In every instance, the opinions given are based upon the known sciences as manifested through the medium of the arts, and more particularly the electric telegraph.I have reviewed the early semaphore telegraphs, and ex plained their respective modes of operation. These visual systems have, however, ceased to be employed by civilized nations, except for the marine service.As preliminary to the consideration of the electric telegraph, I have introduced a few chapters explanatory of the sciences immediately blended in that art; such, for example, as static and voltaic electricities, magnetism, and electro-magnetism. These questions of philosophy the telegrapher should most carefully study. The data given are from the most reliable authorities.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis 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.