ALFRED P. GAGE, PH.D. AUTHOR OF "ELEMENTS OF PHYSICS," "INTRODUCTION TO BOSTON, U.S.A., AND LONDON 1901 PREFACE. It is now thirteen years since my Elements of Physics was published. In the interim many changes in the technical nomenclature of Physics and many improvements in methods of presentation of portions of the science have been made, and, above all, the whole subject of Electricity and Magnetism has outgrown its former apparel. Furthermore, the present is conceded to be an era of extraordinary scientific activity, and the demand for frequent revisions of scientific text-books is correspondingly imperative. The present volume, however, is a new work, and not a mere revision of former works. Much of the material of previous works, when suited to present needs, has naturally been incorporated into this; but everything has been carefully rewritten and rearranged with reference to its adaptability to the requirements of the present day. The considerable increase of volume and scope of this work over those of its predecessors may require some explanation. In this book I have naturally been moved to attempt to meet the demands of many highly esteemed critics who have complained of serious omissions in my former works, and I am apprehensive solely lest this volume also may fall short of the requirements of many. Then, too, as was suggested above, the scientific activity of this age results in successive additions both to the theory of Physics and to its application, and thus tends to make the ground covered by new text-books continually greater. |