Experimental Science. By George M. Hopkins. This book treats on the various topics of Physics in a popular and practical way. It describes the apparatus in detail, and explains the experiments in full, so that teachers, students and others interested in Physics may readily make the apparatus without expense and perform the experiments without difficulty. The aim of the writer has been to render physical experimentation so simple and attractive as to induce both old and young to engage in it for pleasure and profit. A few simple arithmetical problems comprise all of the mathematics of the book. Many new experiments are here described for the first time. It is the most thoroughly illustrated work over published on Experimental Physics. 840 pages. Over 790 illustrations. Seventeenth edition. Revised and enlarged. 8vo, cloth $4.00 Explosives. Lectures on Explosives. A course of Lectures prepared especially as a Manual and Guide in the Laboratory of the United States Artillery School. By Willoughby Walke, First Lieut. Fifth United States Artillery. Second edition. Revised and enlarged. 8vo, cloth. 435 pages. New York, 1897 $4.00 Feeds and Feeding. A Handbook for the Student and Stockman. By W.A. Henry. 8vo, cloth. 657 pages. 1898 $2.00 Our large Catalogue of American and Foreign Scientific and Technical Books, embracing more than Fifty different subjects, and containing 116 pages, will be mailed, free, to any address in the world. Any of the foregoing Books mailed, on receipt of price, to any address. Remit by Draft, Postal Note, Check, or Money Order, to order of MUNN & CO., 361 BROADWAY, NEW YORK. A COMPLETE ELECTRICAL LIBRARY BY PROF. T. O'CONOR SLOANE, Comprising five books, as follows: Arithmetic of Electricity, 138 pages $1.00 Electric Toy Making, 140 pages 1.00 How to Become a Successful Electrician, 189 pp. 1.00 Standard Electrical Dictionary, 682 pages 3.00 Electricity Simplified, 158 pages 1.00 The above five books by Prof. Sloane may be purchased singly at the published prices, or the set complete, put up in a neat folding box, will be furnished to Scientific American readers at the special reduced price of Five dollars. You save $2 by ordering the complete set. Five volumes, 1,300 pages, and over 450 illustrations. Send for full table of contents of each of the books. Our complete book catalogue of 116 pages, containing reference to works of a scientific and technical character, will be sent free to any address on application. We cannot permit the receipt of Sloane's Electrical Library to pass by without complimenting you upon the same. It is a most admirable work. Should be in the hands of all those who are interested in electricity. PHILLIPS, ORMONDE & CO., Engineers. Melbourne, Victoria.