WATER. Its Purification and Use in the Industries. By William Wallace Christie. New York: D. Van Nostrand Company, 1912. 8vo.; 219 pp.; illustrated. Price, $2 net. The material of this work is a compilation of the apparatus and processes in practical use for the purification of water. The distinguishing features of each machine are admirably picked out by the aid of diagrams and colored inserts. There is much in the way of general information also, and there are numerous tables that cannot fail to be of use to engineers and manufacturers. Water softening, pressure filters and aeration, and the measurement of water, are some of the other headings under which the author writes. Tables, equivalents, and definitions conclude a well-written and informing work. VOLCANOES. Their Structure and Significance. By T. G. Bonney, Sc.D., LL.D., F.R.S. New York: G. P. Putnam's Sons. 8vo.; 380 pp.; illustrated. Price, $2. While Prof. Bonney has little, if anything, to say that has not been said before, he has given us a work at once scholarly and entertaining, which in this third edition presents certain alterations and additions that enhance its value by bringing it up to date. Especially is this true in regard to the sixth chapter, dealing with the theories of volcanic action, in which the inferences resulting from modern study are indicated. The destructive eruptions of the Soufrire in St. Vincent and Mont Pele in Martinique have made these volcanoes the objective of scientific investigators, and the results of their study have been incorporated into the present edition. GAS ENGINE PRINCIPLES. With Explanations of the Operation, Parts, Installation, Handling, Care, and Maintenance of the Small Stationary and Marine Engine, and? Chapters on the Effect, Location, Remedy, and Prevention of Engine Troubles. By Roger B. Whitman. New York: D Appleton & Co., 1912. 12mo.; 248 pp.; illustrated. Price, $1.50 net. The sub-title is a sufficient indication of the scope of the work, which is well and profusely illustrated, and set up in such clear type, and with so careful an attention to appearance, that it is a pleasure to run over the pages. The inexperienced owner can not fail to absorb from this text-book information that will greatly alleviate his troubles. The work is unencumbered by any discussion of design, or by comparisons of the merits of various constructions. GAS POWER. By C. F. Hirshfield, M.M.E., and T. C Ulbricht, M.M.E. New York: John Wiley & Sons, 1913. 8vo.; 209 pp.; 60 figures. Price, $1.25 net. This is an elementary treatise in which the problem of the heat engine is discussed, the principles of external and internal combustion are set forth, and such subjects as historical development, fuels, methods, accessories, types, and practice, all receive consideration. It is the manual training school student, and others of limited technical education, toward whom the text-book is directed. THE GAS TURBINE. Theory, Construction, and Records of the Results Obtained from Two Actual Machines. By Hans Holzwarth. Translated by A. P. Chalkley, B.Sc. With additional notes by the Author. Philadelphia: J. B. Lip-pincott Company, 1912. 8vo.; 140 pp.; 142 illustrations. Price, $2.50 net. The author spent three years on the development of a practical gas turbine, and his solution of what he truly calls an important technical problem is very adequately set forth in this translation. Part I of the work deals with description and theory; Part ? with construction. Part ?? draws a general comparison between the gas turbine and the reciprocating engine, first treated thermody-namically, and afterward from the point of view of construction and operation. Part IV deals with the results of tests. STEAMSHIP CONQUEST OP THE WORLD. By Frederick A. Talbot. Philadelphia: J. B. Lippincott Company. 8vo.; 344 pp.; illustrated. Price, $1.50 net. The author has given us quite an enthralling story of the development of water transportation. The North Atlantic is naturally the predominating scene, since the fight for maritime supremacy here wages the fiercest. The general reader may learn, while at the same time being thoroughly entertained, of the operations of ship building from the laying of the keel to the launching of the monster liner. The luxury of the modern passenger vessel is strikingly shown in pictures of the appointments and fittings of such carved, paneled, and painted halls as are found in the Deutschland, the Mauretania, the Olympic, and their kin. The great fresh-water liners are also pictured and described, and steamless ships furnish an interesting chapter. STEAM BOILERS. Their Theory and Design. By H. de ?. Parsons, B.S., M.E. New York: Longmans, Green & Co., 1912. 8vo.; 377 pp.; illustrated. Price, $4 net. This fourth edition of a favorably-known work makes its particular bid for notice on the fact that it covers the most perplexing points to be found in practical office work. The reader's acquaintance with boiler-shop practice is taken for granted. The work surveys its field with a great degree of thoroughness, and its merits have been recognized by students and by the engineering profession.