This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890 Excerpt: ...of 2 inches. An alteration was made to the ends of the drill-machines, consisting of a cast-steel block driven on the piston; the end is bored taper to receive the drills, which are turned to fit. They were then placed in the block, and the first movement of the machine fixed the drill, which could be easily removed by a cotter driven into the slot of the block. This end kept the drill perfectly true with the axis of the machine, and made the boring far easier. The machines were mounted on hydraulic columns. No holes were drilled deeper than 3 feet; the diameter of hole at the commencement was about 2? inches, diminishing to 1? inch at the point. The drill-machines gave every satisfaction, only eight were used, of which two were worn out, and six remain in good order. The...