MR. FISHER'S book is another example of the Electrician series of technical manuals, written by specialists for those engaged in electrical work. They generally contain very valuable information which could hardly be obtained, except by the expenditure of much trouble, from any other source; they are written with a knowledge of what is important for, at any rate, the practical reader, and they are illustrated in most cases by well-executed drawings of instruments and machinery. All these merits Mr. Fisher's book possesses. It is clear and concise, and has a distinct firsthand value of its own, as the work of one who has himself made the tests and investigated most of the questions which he discusses. The Potentiometer and its Adjuncts. By W. Clark Fisher Pp. x + 194. (London: The Electrician Printing and Publishing Company, Ltd.) The Principles of Alternate Current Working. By Alfred Hay, Lecturer on Electrotechnics at the University College, Liverpool. Pp. xi + 276 + iv. (London: Biggs and Co.) Electric Wiring for the Use of Architects, Underwriters, and the Owners of Buildings. By Russell Robb. Pp. 183. (London and New York: Macmillan and Co., 1896.)