ROOTS' FORCE BLAST BLOWER, [Illustration: Roots blower] FIRST PREMIUM AWARDED AT PARIS AND VIENNA, SPEED ONLY 100 TO ??0 REV. PER M. SAVES HALF THE POWER REQUIRED FOR FAN. P. H. & F. M. ROOTS, Manuf'rs, CONNERSVILLE, IND. S. S. TOWNSEND, Gen'l' Ag't, 6 Cortlandt St., NEW YORK. ESTABLISHED 1844. JOSEPH C. TODD, (Formerly of Todd & Rafferty), ENGINEER AND MACHINIST. Flax, Hemp, Jute, Rope, Oakum, and Bagging Machinery, Steam Engines, Boilers, etc. Also Agent for the celebrated and improved Rawson & Rittinger Hoisting Engine, I will furnish specifications and estimates for all kinds of machinery. Send for descriptive circular and price. Address J. C. TODD, 10 Barclay St., New York, or Paterson, N. J. GUILD & GARRISON, [Illustration: Pump] 34 to 44 First St., Williamsburgh, N. Y., Manufacturers of STEAM PUMPS for all purposes. Also Vacuum Pumps, Vacuum Fans and Air Compressors. NON-COMBUSTIBLE STEAM BOILER AND PIPE COVERING WITH "AIR SPACE" IMPROVEMENT. Saves 10 to 20 per cent. CHALMERS SPENCE CO., Foot E. 9th St. N. Y.; 1202 N. 2d St., St. Louis, Mo. NEW WOOD LATHE; ALSO SCROLL SAW. BOTH new and first-class. Send for circulars. H. BICKFORD, Cincinnati, O. ROCK-DRILLING MACHINES AND AIR COMPRESSORS MANUFACTURED BY BURLEIGH ROCK DRILL CO. SEND FOR PAMPHLET. FITCHBURG MASS MACHINISTS' TOOLS. NEW AND IMPROVED PATTERNS. Send for new illustrated catalogue. Lathes, Planers, Drills, &c. NEW HAVEN MANUFACTURING CO., New Haven, Conn. STEEL CASTINGS, From ¼ to 10,000 lbs. weight, true to pattern. An invaluable substitute for forgings, or for malleable iron castings requiring great strength. Send for circular and price list to CHESTER STEEL CASTING COMPANY, EVELINA STREET, PHILADELPHIA, PA. [Illustration: Planer Saw teeth] FULL SIZE PLANER SAW TOOTH 3 CENTS EACH "OFFICE OF DICKINSON BROS., RIDGEWAY, ELK Co., PA., May 28th, 1877. "Messrs. EMERSON, SMITH & Co. GENTS: We have been through four winters in frozen hemlock, cutting 20,000 feet of lumber per day with your Patent Planer Saw, averaging 75,000 feet with each set of 40 bits." --> Mill Men and Sawyers, send your full address, plainly written, on a postal card, for Emerson's Hand Book of Saws, free, to EMERSON, SMITH & CO., BEAVER FALLS, PA. Please name size and style of saw used. [Illustration: LEHIGH VALLEY EMERY WHEEL CO.] Machines AND Wheels Guaranteed, Send for Illustrated Circular, _Weissport_, PA. PERFECT NEWSPAPER FILE The Koch Patent File, for preserving newspapers, magazines, and pamphlets, has been recently improved and price reduced. Subscribers to the SCIENTIFIC AMERICAN and SCIENTIFIC AMERICAN SUPPLEMENT can be supplied for the low price of $1.50 by mail, or $1.25 at the office of this paper. Heavy board sides; inscription "SCIENTIFIC AMERICAN," in gilt. Necessary for every one who wishes to preserve the paper. Address MUNN & CO., Publishers SCIENTIFIC AMERICAN. HARTFORD STEAM BOILER INSPECTION & INSURANCE COMPANY.