Magnetism and Electricity

Abstract

DR. GUTHRIE has evidently devoted considerable time and care to the preparation of this text-book. It has undoubtedly a freshness and originality of treatment which, though apt to shock electricians in parts, yet places this treatise in striking contrast to some science class-books of mushroom growth, that bear the mark of scissors and paste on every page. In such books the text too often seems written to illustrate the threadbare woodcuts; here, however, the illustrations are original, and usefully aid the author's meaning. It is true in some cases the cuts are rough and poorly engraved, e.g. Figs. 90, 105, 107, 112, 123, 183, and 274, and it is to be regretted that, in the case of instruments at any rate, the illustrations are not drawn to scale but often greatly out of proportion, the reason for which, the author states, is better to show principles; but this hardly applies to apparatus which the student or instrument maker may have to construct from the figures. We like, however, the quaintness seen in many of the terms employed; such as the use of “tandem” to describe cells grouped in simple circuit by “joining the family of zincs to the family of carbons” (p. 183), and the term “abreast,” employed to indicate the compound circuit; a source of voltaic electricity is called an “electrogen,” and the transport of the products of electrolysis is termed “migration of the ions,” &c. Some of the illustrative analogies given by the author are also very happy, as, for example, the ease with which the molecular transfer is effected in electrolysis is compared to the ease with which a chain hanging over a pulley is moved: “When the two sides are equal each link on one side may be conceived as keeping in equilibrium the opposite link on the other side. A slight force pulling one side down will bring each link opposite to a different one” (p. 137). Incidentally, one or two of the new things strike us as open to question: for instance, the habitual use of the word isolate instead of insulate; the former has a French aspect, and certainly is less familiar to English readers than the latter term. Again, the omission of all names of discoverers, because, the author states in the preface, “the book is not a history of discovery;” nevertheless, is it not well that students should be able to associate with Faraday's name, for instance, the famous discoveries he gave to the world? and with all the author's care one or two less important names have crept in, that thus have an undue prominence given to them. On the other hand the unostentatious tone of the book and the entire omission of any reference to the writer, even in the description of the instruments he has devised or the facts he has discovered, are excellent traits, and quite characteristic of the author.

Magnetism and Electricity.

By F. Guthrie, Professor of Physics at the Royal School of Mines. (London and Glasgow: W. Collins, Sons, and Co., 1876.)