The hammer proper has four holes bored out, through which the rods pass. As these rods are turned the entire length, and the holes in the ham mer bored out with just sufficient play, it is evident that the hammer can not cast and break the piston-rod. Breakage of the bonnet is avoided by placing the rods in the corners of the bonnet, leaving the full section of the metal between unimpaired by bolt or rivet holes. The action is regular and continuous. The manufacturers claim that any kind of pile can be used, hard or soft, straight or crooked, and driven to any depth without injury to the head of the pile, in the hardest kind of driving, sand or hard pan ; and that the most ordinary kind of timber, such as spruce, bass, and pine, can be thus driven withont the use of head bands.
The following table shows the dimensions of these hammers: Crer Pile, Drivers are widely used in the construction of railroads. These are of especial construction, and must possess great capacity, dura F,G.5.—stea„, pile bility, and facility of operation in order to hammer. keep pace with the phenomenal rapidity of the track layer. A novel form of apparatus, swivelling on the centre to work at either end, is represented in Fig. 6. The type of hammer employed is the steam ham
mer last above described. The dimensions are as follows : Length of car, :11 ft.; centre of forward axle to centre of pile, Si ft.; centre of forward axle to centre of pile, with forward truck moved back, 16 ft.; lateral swing either side of centre, 9 ft. ; extreme height above top of rail, with leaders lowered, 15, ft.; total length of leaders t o under side of head block, 3Gft.; weight of drop ham e r, 2,000 lbs The leaders a r eraised a n d lowered b y the engine.
The swing ing pinions are operated b y ratchet wrenches.
The car it self is symmetrical about the pivot point, so that the carriage may be swung around end for end. Driving can be done at either end, with equal ease. The machine may be made self propelling, and this mechanism is likewise quite independent of the position of the carriage upon the car, whether at one cud or the other, central, or swung out at work. The engine is of a special form, and the boiler is upright to save length. We are indebted to the Vulcan Iron Works of Chicago for the foregoing information.