London: C. J. CLAY AND SONS, CAMBRIDGE UNIVERSITY PRESS WAREHOUSE, AVE MARIA LANE. Cambridge: DEIGHTON, BELL, AND CO. Leipzig: F. A. BROCKHAUS. OF NATURAL PHILOSOPHY BY SIR WILLIAM THOMSON, LL.D., D.C.L., F.R.S., PROFESSOR OF NATURAL PHILOSOPHY IN THE UNIVERSITY OF GLASGOW, PROFESSOR OF NATURAL PHILOSOPHY IN THE UNIVERSITY OF EDINBURGH. Cambridge: AT THE UNIVERSITY PRESS. 1890 [All Rights reserved] Lh •K29 •2 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 among those not ordinarily attacked without the help of the Differential Calculus, have here been found to yield easily to geometrical methods of the most elementary character. "Simplification of modes of proof is not merely an indication of advance in our knowledge of a subject, but is also the surest guarantee of readiness for farther progress. "A large part of Chapter VII is reprinted from a series 21239 |