Physics The Elements

PHYSICS THE ELEMENTS Tapacrcret rows avdpanrovs ov ra aXXa ra irepl raJi irpayyidro v Sdy xara j f the facts, but the explanation of them, matters PHYSICS THE ELEMENTS BY NORMAN ROBERT CAMEEELL, Sc. D., F. INST. P. A MEMBER OF THE STAFF OF THE RESEARCH LABORATORIES OF THE GENERAL ELECTRIC COMPANY, LIMITED, LONDON CAMBRIDGE AT THE UNIVERSITY PRESS 1920 PREFACE THE object and nature of this book is sufficiently explained in the introduc tion here I will only warn the reader who gets no further that, in spite of its title, it is not an elementary treatise on physics. On the other hand, although there is a just prejudice against an author who seeks to disarm criticism, I would explain here how the book came to be written not in order to explain its faults away, but in order, by giving notice of them, to render them less harmful. The book was planned in 1904 and from that time onward parts of it were written in the form of separate essays as various problems forced them selves on my attention in the course of the ordinary scientific work which occupied most of my time. Some of these essays have been already published in their original form in various Reviews and in a little book called The Principles of Electricity Jack, 1912. At the end of 1912 all the present chapters, and some others, were written in that form but since they had been written independently and my views had naturally developed in the writing of them, coordination was needed. I began the work, but was interrupted, first by the preparation of a new edition of another book, and then by the war. In 1919 an opportunity for completing the book occurred, better than was ever likely to occur again. But it was not entirelyfavourable time was limited to eight or nine months, and the work had to be done in the country, without access to libraries or even to my own collection of books. Moreover, I found that I had forgotten about the matter so completely that, at the outset, the manuscript might have been that of an unknown author. It would have been wiser to read it, burn it, and start afresh but in a mistaken attempt to save time, the old material was used and though everything except the Introduc tion has been re-written, at least half of it is practically a mere transcript. There were two reasons for preserving the Introduction with as few alterations as possible. First though, unlike most introductions, it was actually written before the rest of the book, I found that I had really carried out my plan and had stated my intention as well as I could state it now. The second reason is personal piety. When the chapter was first written it was sent to my friend, Charles Donald Robertson, with whom, although his tastes were literary rather than scientific, I had often discussed with much profit the principles of science. It was found among his papers after his death in 1910, and returned to me. Two faults arise from these circumstances. The coordination of the separate essays is still incomplete, and there are several instances which I leave the reader to discover, if he is sufficiently interested where the point of view is rather different in different parts of the book. On the whole I vi PREFACE attach more value to the later portions. The most serious inconsistency arises in a reference in the earlier chapters to Part III, which is not included in the present volume it was only when half the book was intype that it was de cided to omit this Part, both on account of lack of time and because the volume would be too bulky, A summary of some of the conclusions of that Part are given in an appendix. And here perhaps a brief account should be given of the plan of the remainder of the treatise. Part III, under the title Motion, deals with temporal and spatial conceptions. Part IV, Force, with statics and dynamics, both classical and modern. Part V, Energy, with the doctrine of energy, especially in its application to heat, thermodynamics and radiation...