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 subject like this will not necessarily be unscientific or inaccurate because it is couched in language nearly free from technical terms and mathematical formulæ. That it must be less complete and exhaustive goes without saying; but the design of the author, as already intimated, is to present a sketch. Any reader who is so disposed will have no difficulty in finding material for filling in the details with any desired degree of elaboration. WASHINGTON, D. C., May 16, 1886. T. C. M. |