HENLEY'S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED TRADES. Edited by Joseph G. Horner. 6 volumes of about 500 pages each, 99 3/4 x 7 1/2 inches. Copiously illustrated. Price, per set, $25; per volume, $6. Norman W. Henley Publishing Co., New York.

It is not an easy task to properly present the merits of such an extensive work as this, as its very character prevents other than a statement of the degree of skill and knowledge used in its compilation. The ability of the editor-in-chief is ample assurance that in these respects it would be entirely satisfactory, if we accept the method or classification, and even here preferences differ. In general, each topic and subdivision of a topic is presented under its separate heading, in preference to a single division with subheads. Exception are found to this however, as under "Drills," is found "Counter-bores, " while "Twist Drills" are separately treated. This is a minor matter, however, and to others than the technical reader, will not be found detrimental to the best use of the work.

It is very comprehensive in its scope and quite up-to-date, tools being mentioned which been but lately put upon the market. It is more especially devoted to mechanical subjects, althoug civil engineering subjects receive due consideration. Processes are given prominent treatment, whenever their impartance warrants it, giving the volumes a more practical character than ordinarily is the case. The illustrations are most excellent; the text and type are clear and easily readable. For public, school and shop libraries, as well as the mechanic whose means will permit of its purchase, this publication should be particularly valuable, and it deserves their extended patronage.