IN ELEMENTARY PHYSICS. BY BALFOUR STEWART, M.A., LL.D., F.R.S. LATE LANGWORTHY PROFESSOR OF PHYSICS IN THE OWENS COLLEGE, NEW AND ENLARGED EDITION. London MACMILLAN AND CO. AND NEW YORK. 1888. The Right of Translation and Reproduction is Reserved. First Edition printed November, 1870. Reprinted March and May, 1871, 1874, 1875, 1877. New and Enlarged Edition, printed Jan. 1878. Reprinted 1879, 1880, 1881, 1882, 1883, Jan. and Nov. 1884, 1885, 1886, 1887, January 1888. New and Enlarged Edition, June 1888. PREFACE TO THE FIRST EDITION. IN the following pages I have endeavoured to bring before the student, in an elementary manner, the most important of those laws which regulate the phenomena of nature; but the subject is so extensive that a detailed account cannot be given in such a treatise as this. The various branches of the subject have been so arranged that the student may perceive the connexion between them. For many particulars of this arrangement I am indebted to my friend Professor Tait. An account of the various active agents, heat, light, electricity, &c., must always form a large portion of a work on Physics. These have been regarded as varieties of energy -the laws of energy forming, as it were, the thread upon which the various divisions of the subject are strung together. The description of these agents is not, of course, materially different from that usually given; but by this means of connecting them together, the student is constantly reminded of the paramount importance of the laws of energy. For the plate representing various spectra, which forms the frontispiece, and for that of the Kew spectroscope, I am indebted to my friend Mr. Lockyer; and I have much pleasure in thanking Mr. George Whipple, of the Kew Observatory, for many suggestions while the work was passing through the press; and also Mr. J. D. Cooper and Mr. Collings for the care they have bestowed upon the illustrations. MANCHESTER, October, 1870. PREFACE TO THE EDITION OF 1877. IN the present edition some new matter has been introduced, more especially in the chapter which treats of Sound. I am much indebted to Professor Core, of Manchester, and to Mr. Bion Reynolds, M.A., for assistance and suggestions, and I may take this opportunity of stating that Professor Core intends shortly to publish a book of questions founded upon these Lessons. December, 1877. PREFACE TO THE EDITION OF 1885. THE chief alteration in the present edition is the introduction, near the end of the volume, of a short sketch of the more prominent practical applications of electricity which have recently been made. I am indebted to the kindness of Mr. Kenneth Romanes for pointing out several errors, chiefly typographical, which I have now corrected. September, 1885. PREFACE TO THE PRESENT EDITION. THE sheets of this new edition were finally revised by the late Professor Balfour Stewart up to p. 192. He had also made a first revise up to p. 304. The edition has been completed by Mr. W. W. Haldane Gee, B.Sc., Lecturer of the Victoria University. The chief changes introduced have been in the chapters relating to Electricity and Magnetism, which have been rearranged and new figures and additional matter included. This has been done in accordance with the expressed intention of Dr. Stewart. The reviser is indebted to Professor T. H. Core, M.A., for his advice respecting several of the alterations that have been made, and for kindly reading through the proofs. June, 1882. |