A CENTURY OF ELECTRICITY BY T. C. MENDENHALL SUPERINTENDENT U. S. COAST AND GEODETIC SURVEY BOSTON AND NEW YORK 1892 Copyright, 1887, 1890, BY T. C. MENDENHALLO All rights reserved. TIBBYBA The Riverside Press, Cambridge, Mass., U. S. A. Mc Clure En537 ро PREFACE. A HUNDRED years have elapsed since the experiment of an Italian philosopher inaugurated a new era in physical science. The industrious cultivation of the new electricity from that day to the present has been so fruitful of results, that even the specialist has found difficulty in keeping pace with its development. Within a few years it has found its way into the household, and hundreds of thousands of intelligent people have come to have some personal familiarity with its use. It is believed that this familiarity has not "bred contempt," but rather that it has excited a desire, on the part of many, to know something of the fundamental principles which underlie its numerous applications, and to learn something of the evolution of these principles. In this belief, the author has endeavored to sketch the growth of the science of electricity, and its principal applications. The book is not a history of the science, nor is it a scientific 248131 treatise; but the author trusts, that, as far as it goes, it is not far wrong in either its history or its science. The use of technical language has been avoided as far as possible; and the effort has been to enable the intelligent reader, unfamiliar with the nomenclature of the science, to understand the more important phases of its development, and to give him such a knowledge of its fundamental principles as will enable him to comprehend the meaning of what he sees in electrical devices, with which he almost daily comes in contact. It has been assumed that the interest of the reader in the discovery of a principle or fact will not be lessened by a little knowledge of the personality of the discoverer, especially when his name has become a part of the nomenclature of the science. The literature of electricity is now so extensive, that it would be difficult to enumerate the sources from which the writer has drawn in the preparation of this volume. In many instances original memoirs have been consulted, and where direct quotations are made that fact is indicated. It is with great reluctance that the author consents to add another to the already large number of so-called "popular" books on electricity; but he believes that the treatment of a |