ROPP'S NEW CALCULATOR is from beginning to end an entirely new, reconstructed and vastly improved publication. It contains a new system of tables, new rules, short-cuts and up-to-date methods; also 48 cuts, illustrating the principles of mechanics and mensuration. It has more than double the contents of the old edition, of which Over a Million Copies Were Sold It is the CALCULATOR that positively calculates, instantly and correctly-not merely a limited number of easy examples, as ordinary Ready Reckoners, but almost every conceivable example or problem that is likely to occur in daily business transactions, whether the given quantities be large, small, even, odd or fractional numbers. ROPP'S NEW QUADRUPLEX SYSTEM is by far the greatest labor-saving improvement ever devised in the construction of mathematical tables, and is as simple and plain as it is new and unique. It consists of an ingenious arrangement of different sized figures, so spaced as to always show the whole answer at a glance, however large the given numbers, thus saving the labor, time and trouble of looking for, and of combining, three or more partial answers scattered over as many pages or columns to find the total answer. ROPP'S NEW CALCULATOR is the consummation of devising and improving system after system; of expending thousands of dollars in experimenting: of making millions of miscellaneous calculations, and of doing a vast amount of vigorous thinking, during more than 35 years, by an analytic, practical and persevering mind. It prevents mistakes, relieves the mind, saves labor, time and money. Makes you independent, sure and self-reliant in figures. A great paper says: "A new publication that must prove of incalculable benefit to the commercial worldunless the book itself can calculate its own worth-for it calculates almost everything that is calculable." You can get a copy of Ropp's Calculator FREE in connection with a subscription to Modern Machinery Modern Machinery is our monthly machinery journal which tells you every month all about the progress in new machinery made all over the world, well illustrated and interestingly written. Subscription price, $1.00 per annum (12 issues); single numbers, 10 cents. Everybody should read Modern Machinery to keep abreast of the times in this age of mechanical invention. SUBSCRIBE NOW AND RECEIVE ROPP'S CALCULATOR FREE OF ALL CHARGES. Gentlemen:-Enclosed find $1.00, for which please send me Modern Machinery for one year, and also send me, free of all charges, Ropp's New Calculator. Name. City. State Let The Gillette Prove Itself Shave with it every day for a month. Then if it hasn't proved our claims for it-if for any earthly reason you'd rather have your money than the razor- Return the Razor! Your Money Back and Welcome That's the spirit of our guarantee and the practice of it. We could not send the Gillette on 30 Days Trial if it did not make good-satisfy the most particular man (and a man has a right to be particular about his shaving). The Gillette is a safety that is a safety-and it's a razor, too. In fact it is 24 Razors In One It has twelve keen doubleedged blades as thin as paper, tempered and glass hardened by our process so that it takes diamond dust to grind them. Each blade gives ten to thirty perfect shaves. Case and blades packed and sealed direct from the factory, showing them to be new. Always ready to use GILL No Stropping or Honing LITERATURE-(Continued) Handy Lumber Tables. The Industrial Publication Company, New York, N. Y., Pages24. Price 10 cents No LABOR-SAVING DEVICE is more effective than a good set of tables. By the use of this little book, every person who has to do with lumber in any form will not only save valuable time, but avoid the occasional errors that are apt to be made by the most expert calculator. It takes but a moment to insert a new blade. You cannot cut yourself or fail to give yourself a smooth, delightful shave. Think of the waits you save, the cleanly delight of home shaving and the economy of it. A Gillette lasts for years. When you have used each of the edges until dull, return to us and we will give you six new blades at no cost to you. Additional blades at nominal cost. The Gift to Please Him Most You cannot place yourself more pleasantly or lastingly in the thoughts of husband, brother, father or friend than by ending his shaving troubles. Give him a Gillette Razor. Triple plated silver, with blades, leather case, sent prepaid, Lectures on Commerce. Edited by Henry Rand Hatfield. The University of Chicago Press. Pages 379. Price $1.50. THIS VOLUME is made up of a series of lectures delivered before the College of Commerce and Administration of the University of Chicago. The lectures are not the work of the regular professors of the University, but are by men of affairs, presidents of railroads, industrial concerns, and banks, heads of advertising firms and steel plants, managers of insurance companies, etc. The University has adopted the wise plan of inviting men who are doing things in the commercial world to address the students of the College of Commerce and Administration. These lectures are plain, practical, uplifting business talks of extreme importance to young men. We cannot recall any work dealing along this line that contains SO much serviceable information as this volume. An excellent index adds much to the value of the work. Complete Working Drawings of a Marine Steam Plant. Published by Marine Engineering, 309 Broadway, New York, N. Y. Price, $1.00. TO THE ORDINARY LAYMAN the tripleexpansion engine is an unsolved mystery of inexplicable complication; and even many an engineer has little more than a $5; will save five times its cost the first year. Special hazy understanding of its mechanism. A Gift Gillette, 20-year guaranteed heavy quadruple gold plate Gillette Razor, in elegant case, $10. Same, in fine Morocco case, with name gilded on case and engraved on razor handle, a magnificent present, $12. most useful purpose, therefore, is served by this collection of drawings, which show graphically, clearly, and in full detail, the latest practice in marine steam Chicago, Ill. engines. While intended, of course, specially for those interested in steam engineering, they will be found to contain Ask your dealer; if he doesn't sell it, get him to correspond with us. At any rate, write for our interesting booklet. Mailed free. THE GILLETTE SALES CO. 1624 Manhattan Building Sales Agents and Manufacturers of Hardware Specialties. References-Continental National Bank, Chicago; Chicago National Bank; Dun's and Bradstreet's. Mention The Technical World. You can't do your best work without best things to work with. If you care for quality in draughtsmen's supplies - papers, academy boards, pencils, crayons; you know what-see that you get Devoe stuff. We make and handle more of these Devoe & Raynolds Company Standard Books for Students and Draftsmen Details of Building Construction. A collection of 33 plates of scale drawings, with introductory text. By CLARENCE A. MARTIN, Asst. Professor, College of Architecture, Cornell University. Price $2.00. Building Construction and Drawing. A text book on the principles and practice of construction. Specially adapted for students in Science and Technical Schools. First stage or elementary course. By CHARLES F. MITCHELL. 5th edition, revised and enlarged. 360 pp. of text, with nearly 950 illustrations. Crown, 8vo.. cloth. Price, $1.50. Building Construction. Advanced and Honours Courses. Third edition, thoroughly revised and greatly enlarged. By CHARLES F. MITCHELL. Containing 660 pp. of text, with 570 illustrations, many being fullpage or double plates of examples, with constructional details specially drawn for this edition. Crown, 8vo., cloth. Price, $2.50. The Principles of Architectural Perspective. Carefully prepared for the use of students and others with chapters on Isometric drawing, and the preparation of finished perspectives. By G. A. T. MIDDLETON, A. R. I. B. A. Illustrated with 41 diagrams, and eight drawings by various architects. Cloth. Price, $1.00. Catalogue of Architectural and Wm.T.Comstock, Publisher 23 Warren Street, New York LITERATURE-(Continued) much of interest also to the general reader. One sheet gives data for studying or designing a 4-furnace, single-end Scotch boiler. Another shows all pipe connections between a triple-expansion engine, the boilers, and the auxiliaries. Another gives details of a 3-cylinder, inverted, direct-acting triple-expansion engine, presenting three views-front, sectional elevation, and elevation and plan. Each part is numbered, and an explanatory key is furnished. Accompanying the sheets is a folder giving the necessary text to explain each. The most costly piece of railroad literature ever issued is the special Southern edition of the SEABOARD MAGAZINE OF OPPORTUNITIES,-yes, there is one for you. It is unique, contains no advertisements, but hundreds of full page and half page photo-gravures-the most exquisite examples of the modern printers' art, and each worthy of framing. Sent free on receipt of 10 cents to pay postage. J. W. WHITE, General Industrial Agent, PORTSMOUTH, VA. SEABOARD AIR LINE RAILWAY Electrical World and Engineer (October 1) - New York ONE OF THE LEADING ARTICLES of this number is that upon the Puyallup River Water-Power Development near Tacoma, Washington. The cities of Tacoma and Seattle have grown very rapidly in the past five years, and electrical developments have kept pace with this growth. The Puget Sound Power Company, the owner of the plant mentioned, was organ Mention The Technical World. WANTED On a Straight Salary Basis three hundred men and women in all parts of the United States to initiate and carry on certain branches of our business. Can use part or all of time. Positions permanent. Salaries increase with experience. A few traveling positions open to right parties. References required. Apply to THE SUCCESS COMPANY Publishers of "Success" Washington Square, New York Address Desk 49 |