SHOP TOOLS.
114
by bolts to a frame carrying another knife edge. The piece ofmetal to be sheared was placed between the two edges, and thepress being set in motion by means of a small hand-pump, theknife was forced through it. A bar 3 inches square was cutthrough in about 2\ minutes. The shears were well adaptedfor cutting rails. The aetion of the puneh was of a similarcharacter, and one man could punch an inch hole in a |-inchiron plate in about half a minute. These machines were lightand portable, the shears weighing about 14 cwt., the punch4| cwt. Mr. Tangye, at the same time, described a hydraulicjack for lifting weights up to 60 tons. Hydraulic power wasalso employed at bis works for stamping purposes, an air vesselbeing employed to produce an intensification of pressure.
In 1869, Mr. Moss of Chicago applied hydraulic pressure forcompressing steel, from which wheels for locomotives and truckswere made.
In 1864, Sir J. Whitworth erected a hydraulic press to forgeand to press fluid steel, and the result showed such advantagesover hammer forging, that another was erected in 1870, with a24-inch cylinder working at a pressure of 2 tons to the squareinch. Two others having 30 and 34-inch cylinders followed,with a pressure of 3 tons to the square inch, although the workingpressure rarely exceeded 2 tons to the square inch. The forgingpresses are all worked by single cylinders in the press headsIn that for pressing fluid steel there are three cylinders belowthe base plate, which is raised by them. On it is a mould con-taining fluid steel which is pressed against a fixed plunger inthe press head. By the application of intense pressure to fluidmetal in a mould, its whole length can be diminished one-eiglithin less than five minutes, the air cells being expelled. Thetwo screw propeller shafts of H.M.S. Inflexible were made frompressed metal a few years ago at the Whitworth works. Theywere 283 feet in length, 17 inches in diameter, with a 9-inchhole through them. They weighed 63 tons, compared with 97tons, which it was estimated would have been the weight ofwrought iron shafts. The strength of the compressed metal