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Smith Machine for making Thimbles or Sockets for Steam Boilers. Can make over 800 per day, all uniform in diameter and perfectly parallel, leaving no space for the bolts to bend in the thimble, making it almost impossible to make a tight boiler, for when the hydrostatic pressure is applied, straighten the bolt enough to make it leak; often has to be taken out. Address JAMES T SMITH, People's Machine & Boiler W'ks, Baltimore, Md
VENTILATION.—GREAT IMPORTance of ventilation. The vitiation of air that is constantly going on in inhabited places, exhaustion of oxygen by gas, candles and lamps. Ventilation by natural and artificial means. Contained in Scientific American Supplement, No. 525. Price 10 cents. To be had at this office and from all newsdealers.
A BIG OFFER. To introduce them, we will Give Away, 1,000 Self-Operating Washing Machines. If you want one send us your name, P. O. and express office at once. The National Co., 23 Dey St., N. Y.