PREFACE TO THE SECOND EDITION. IN the present wholly revised edition, a large number of important alterations and additions have been made, with the view of giving an account of the numerous inventions which have during the last two years been made in practical electricity. The necessity of a second edition twelve months after the publication of the first clearly shows the general interest taken in the subject which is treated in this book; and, on the other hand, the necessity of dividing the book into two volumes must be ascribed to the enormous progress electrical appliances have lately made, and are making daily and hourly. As a practical illustration of this progress, I may mention that this preface has been set up in type by a composing machine which is worked by electricity. In the first volume a considerable number of electric generators and arc lamps have been added to those given. originally, and a better account of the incandescent lamps. will, I trust, be likewise acceptable. The descriptions and illustrations of these additions are mostly taken from that |