Page:Miscellaneous Papers on Mechanical Subjects.djvu/113

 were undergoing repair and alteration in New York, with the view of making the heated air act alternately upon each side of the piston, similarly to steam in an ordinary engine. The bottom of the cylinder is made of wrought iron, and arched. The upper part, in which the piston works, is of cast iron, and is connected to the lower part by bolts; it was the lower portion which proved defective in strength.

PITTSBURGH, PHILADELPHIA, LAWRENCE, WORCESTER.

7. Iron Castings.—The iron castings in some of the establishments were very good, and cylinders from 8 to 14 feet in diameter were well bored, with a finishing feed of cut of about three-eighths of an inch per revolution, which is a