An Introduction to the Theory of Electricity

Abstract

MR. CUMMING deserves our thanks for having made an effort to introduce into elementary teaching the advances in the treatment of electricity made chiefly by the labours of Green, Thomson, and Clerk-Maxwell. Mr. Cumming possesses all the qualifications necessary for such a task. He evidently has a full knowledge of the subject, and seems to possess, in addition, experience as a teacher. He has had, no doubt, great difficulties to encounter. These difficulties are not alone due to the limitations as to the mathematicial knowledge of his readers, which Mr. Cumming has justly imposed on himself. The books and papers out of which Mr. Gumming had to take his material, were written from various points of view, and they were chiefly addressed by scientific men to scientific men. It was natural that the same words should not be always used exactly in the same sense, the great object being that men already possessing a knowledge of the subject should understand each other. It is only when the knowledge of a certain subject is comparatively advanced that the terms settle down into a definite meaning. A text book, on the other hand, is addressed to students who at the most have only a slight acquaintance with the subject, and it should not only teach that particular subject, but also scientific method, and scientific reasoning. It is, therefore, of primary importance that the precise meaning of the term should be scrupulously adhered to. Even a good definition does not always ensure this, for there is often a metaphysical colouring which does not come out in the definition, but which we soon discover in the way a term is used. We take one example. The word potential is defined by Sir Wm. Thomson thus:—

An Introduction to the Theory of Electricity.

By Linnæus Cumming, M.A. (London: Macmillan and Co,, 1876.)