TUFTS COLLEGE SCIENCE AND INVENTION-(Continued) placed and clamped rather freely by a coarsely threaded hand nut, and finally DEPARTMENT OF pinched tightly by a set screw, the tapENGINEERING ping being done in a lathe or tapping machine as desired. Civil, Mecbanical, Electrical A is a cast-iron holder with a pipe and Chemical Engineering handle; and fitted into it is the steel New Laboratories and Excellent Equipment. Beautiful site within four miles of Boston. Preparatory Department for sleeve B, which has at one end two turns students who have had engineering practice, but insufficient of a very coarse thread whereon is preparation for college work. For information concerning courses and positions of graduates, address H. G. CHASE, Secretary, Tufts College P. O., Mass. The University of Rochester B A College of Liberal Arts Students Rochester, N. Y. DEVICE FOR TAPPING THIN Nuts. screwed the hand nut C. The pin c prevents the sleeve. B from turning in the holder A. Inside B is the inner sleeve D, with the recess d to receive the nut blanks E. A key F prevents D from turning. At its rear end is fitted a disc G, upon which bears the set screw I. whereby the nuts are clamped in. The method of operation is to place the nuts in the recess d, and screw up the nut C by land, which is very quickly done. Then a small part of a turn of the set screw I with a wrench, clamps all firmly for the tapping, upon the completion of which the operations are reversed. EVERETT E. KENT The Verant IN stereoscopes, as is well known, plas- tic vision is ensured through the comCorporations. bination of two separate views of the 84 State Street, BOSTON same object, corresponding to the images formed by the original in each eye respectively. The superposition of these two images produces an impression much llantion The Technical World. ELECTRICAL BOOKS PROGRESS! Is the Watchword in the Electrical Profession and you must keep in touch with the Masters in the Field or you will Rust Out. We can furnish you all of the Latest and Best Books including works All books sent postage prepaid upon receipt of lowest publisher's price 1362 Monadnock Building CHICAGO, ILL. If interested in Telephony, ask for sample copy of “Sound Waves,” The Telephone Journal, when you write for Catalogue Publishers, “SOUND WAVES' PATENTS Valuable and Salable Patents Promptly Secured. Free d d d Write for Inventor's Hand Book Examiner in the U. S. Patent Office to enter this firm. one baving need of the services of a patent attorney." HALLWOOD CASH REGISTER CO. Address, 844 G. St., Washington, D. C. Mention The Technical World PATE PATENTS, SCIENCE AND INVENTION-(Continued) more true to nature than that secured by Valuable Book on Patents FREE. Tells how to a single picture. That similar effects are possible in the case of "monocular" vision, the picture O'MEARA & BROCK, Patent Attys., 918 F. Street, N. W., Washington, D. C. NEW YORK OFFICE, 290 Broadway, New York City: being inspected with one eye only, is CAVBATS, TRADE demonstrated by a novel instrument—the MARKS, COPYRIGHTS "Verant” — just brought out by a firm AND DESIGNS. Send your business direct to Washington. Saves in Jena, Germany. time and insures better service. When viewing, with one eye, photo24 Years Practice. Personal Service Guaranteed. graphs taken with objectives of a focal SIGGERS & SIGGERS, Patent Lawyors, distance noticeably inferior to the so Suite 10, National Union Bldg., Washington, D. C. called distance of distinct vision, viz., 26 PATENTS TRADE MARKS centimeters (10.2 + inches), an observer Obtainod Rogistored of normal visual power is incapable of Suite 45-161 East Randolph Street, CHICAGO obtaining the same angle of vision under Telephone Main 1432 Rogistored Patent Attorney Best service, most reasonable rates. All business strictly confidential. Correspondence solicited. Consultation free. Nomisrepresentations. Freeguidebook on request. PATENTS FREDERICK S. STITT Attorney-at-Law Registered Patent Attorney 15 WILLIAM ST., NEW YORK Patents obtained in the United States and Foreign Countries. Trade Marks registered. Litigation conducted. Examinations. Opinions. PATENTS his eye X SECURED OR FEE RETURNED THE VERANT. sued for free distribution. Patents secured by us advertised A Device for Securing Plastic Vision with a Single Picture free. EVANS, WILKENS & CO. which the objects present themselves to if the latter be placed at the point LOUIS A HILL of the photographic objective and di rected successively to the different points PATENT ATTORNEY of the object. This is why an ordinary 1336 NEW YORK AVENUE picture fails to convey the impression of WASHINGTON.D.C. plasticity which we obtain through the direct inspection of the object the Every me photographs are taken from. Such plaschanic should tic effects could be obtained only by håv & copy of means of a magnified copy of the photoour large 600 page catalogue in his tool kit. The largest graph, which, apart from the additional retail hardware stock in the world at your command. trouble and cost, would be disturbing in Everything for all trades at wholesale prices. We carry both the medium and the very best the case of the image of a distant object grades. Ask for 600 page Mechanics Catalogue. Free to any address. (landscape or building) having to be Montgomery Ward & Co. viewed from a relatively small distance. Michigan Ave., Madison and Washington Sts., Chicago In the verant, a virtual magnification AIR BRUSH The New Art Tool of the photograph is obtained without We have the best art tool in use for good work. Applies color by any additional trouble or cost, so as to jet of air. Saves time and drudgery have the various parts of the image ap in cleaning up. Will send descripFOR tive Circulars Free on request. pear to the eye of an average observer Any interested in fine shading or ART WORK. coloring will do well to investigate. under the same angles of vision as obThe Air Brush Mfg. Co. 134 Nassau St., Rockford, I11., U.S.A. tained when the photograph was taken. Mention The Technical World. Tools UNEL 10 Write at once to |