AUTHOR'S PREFACE THE epoch-making researches of Heinrich Hertz have now given definite confirmation to those 'modern' conceptions of the nature of magnetic, electric and optical phenomena which originated with Faraday, and were further developed by Maxwell and by Helmholtz. Those conceptions have at length become triumphant throughout the entire subject, though they had long to contend with the older theories for supremacy. In the present treatise I have tried the experiment of using the conception of lines of force in the systematic exposition of the phenomena concerned, and have attempted to build up from first principles the laws of Magnetism and of Electricity, in accordance with the latest developments of theoretical knowledge. Many attempts of this kind have already been made, but they are for the most part in the form of special treatises which deal more or less exhaustively with some limited portion of the subject, or which only sketch cursorily the deductive processes involved. So far there has been no convenient text-book developing these new conceptions throughout the whole subject in an easily intelligible manner, so that they may be considered as coming within the scope of a course of lectures on Experimental Physics. The present treatise was, indeed, the outcome of such lectures, wherein I became convinced of the high didactic value which is inherent in the new conceptions. Especial stress was laid on three fundamental 868519 |