ELEMENTS OF NATURAL PHILOSOPHY SIR WILLIAM THOMSON, LL. D., D. C. L., F. R. S., PROFESSOR OF NATURAL PHILOSOPHY IN THE UNIVERSITY OF GLASGOW, PETER GUTHRIE TAIT, M. A., PROFESSOR OF NATURAL PHILOSOPHY IN THE UNIVERSITY OF EDINBURGH. PART I. NEW EDITION. AT THE UNIVERSITY PRESS. 1882 All Rights reserved PEINTBB BY 0. J. CLA. T SON, AT THE ONIVEKSITT PRESS. PREFACE. To the first Edition of this work, published in 1872, the following statement was prefixed The work consists, in great part, of the large-type, or non-mathematical, portion of our Treatise on Natural Philosophy. As it is designed more especially for use in Schools and in the junior classes in Universities, the mathematical methods employed are, almost without exception, limited to those of the most elementary geometry, algebra, and trigonometry. Where higher methods are required for an investigation, the reader is, in general, simply referred to our larger work. It is particularly interesting to note how many theorems, even...