Lunkenheimer "Lever" Throttle Valves Especially adapted as a "Throttle" for traction Designed and guaranteed for working pressures Can be operated by handle or rod attachment from THE LUNKENHEIMER COMPANY Largest Manufacturers of Engineering Specialties in the World 24 The discs have ball and socket bearing between and order from Made in brass, sizes % to 21⁄2 inches, inclusive, and in iron from 2% to 6 inches, inclusive. Cut this out, send to us, and we will mail you a copy of our catalogue. GREAT BURNHAM OLDSENGINES Economical Power In sending out their last specifications for gasoline engines for West Point, the U. S. War Department required them "to be OLDS ENGINES or equal." They excel all others, or the U. S. Government would not demand them. STEAM PUMPS Will not short stroke; neither will they MANUFACTURED BY THE UNION STEAM PUMP CO. 46 S. Madison St., Battle Creek, Mich. "Red Books" are nearly all gone. If you haven't one, send at once. Mention The Technical World. BURNHAM HIGH DUTY PUMP (PHANTOM) BURNHAM 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 hand, 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. The Verant IN N stereoscopes, as is well known, plastic vision is ensured through the combination of two separate views of the same object, corresponding to the images formed by the original in each eye respectively. The superposition of these two images produces an impression much Mention The Technical World. PROGRESS! ELECTRICAL BOOKS All books sent postage prepaid upon receipt of lowest publisher's price Publishers, "SOUND WAVES" 1562 Monadnock Building CHICAGO, ILL. 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 44 If interested in Telephony, ask for sample copy of Sound Waves," The Telephone Journal, when you write for Catalogue P "During the past ten years Mr. Shepherd, of Shepherd & Parker, has obtained for us a great many important patents. We have no hesitation in heartily recommending him to anyone having need of the services of a patent attorney." HALLWOOD CASH REGISTER CO. ATENTS Valuable and Salable Patents Promptly Secured. Advice as to Patentability and Commercial Value Freed Write for Inventor's Hand Book SHEPHERD & PARKER, Patent Lawyers Mention The Technical World Mr. Parker on November 1, 1903, resigned his position as an Examiner in the U. S. Patent Office to enter this firm. Address, 844 G. St., Washington, D. C. SCIENCE AND INVENTION-(Continued) ATENTS P more true to nature than that secured by a single picture. Valuable Book on Patents FREE, Tells how to secure them at low cost. How to Sell a Patent, and What to Invent for Profit. Gives Mechanical Movements invaluable to Inventors, Full of Money-Making Patent Information. NEW BOOK FREE to all who write. O'MEARA & Patent 918 F. N. That similar effects are possible in the case of "monocular" vision, the picture NEW YORK OFFICE, 290 Broadway, New York City. being inspected with one eye only, is PATENTS, CAVEATS, TRADEMARKS, COPYRIGHTS AND DESIGNS. Send your business direct to Washington. Saves time and insures better service. demonstrated by a novel instrument-the "Verant" just brought out by a firm. in Jena, Germany. When viewing, with one eye, photographs taken with objectives of a focal distance noticeably inferior to the socalled distance of distinct vision, viz., 26 centimeters (10.2 + inches), an observer of normal visual power is incapable of obtaining the same angle of vision under which the objects present themselves to his eye if the latter be placed at the point of the photographic objective and directed successively to the different points of the object. This is why an ordinary picture fails to convey the impression of plasticity which we obtain through the direct inspection of the object the photographs are taken from. Such plastic effects could be obtained only by means of a magnified copy of the photograph, which, apart from the additional trouble and cost, would be disturbing in the case of the image of a distant object (landscape or building) having to be viewed from a relatively small distance. In the verant, a virtual magnification of the photograph is obtained without any additional trouble or cost, so as to have the various parts of the image appear to the eye of an average observer under the same angles of vision as obtained when the photograph was taken. Mention The Technical World. |