STATIONARY ENGINES.
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Vertical Table Engine .—We shall now notice the kind of blowingengines called “self-contained,” that is, those erected on one bed platecarrying the whole of the engine. Of this dass are the vertical tableengines, which are constructed for easy transport, all the parts beingas light as possible (Fig. 186). The blowing cylinder Stands on apedestal bolted to the bed plate. The diameter of the cylinder is 30inches; stroke of piston 2 feet 6 inches, making 80 strokes per minute.These engines being small, a greater number of them must of coursebe provided; and when large sizes are adopted the weight of thevarious parts becomes a serious matter. The piston of the blowingcylinder is packed with hemp, with a junk ring to press itdown. The openings for admitting the air into the cylinderare formed on the circumference at the top and bottom; aprojecting flange is cast on at the top and bottom, the barsbetween the opening being inclined, similar to the piston-valve arrangement already described. The valve is of theannular description, encircling the whole cylinder from top Fig ,to bottom; the rubbing surfaces are formed of brass ringsaccurately bored out. The body of the valve is formed of thinwrought-iron plates, securely fastened with a number of small boltsto two cast-iron rings, which are bored out inside for the receptionof the brass packing rings. These rings fit the recesses in thecast iron and face on the cylinder without any other packing; andas they are cut through the wear can be adjusted with a thin slipof metal or paper, and then properly secured with bolts, althoughthere is but little wear with this description of valve, owing to itsbeing perfectly balanced. The air from both ends of the cylinderpasses into the annular space between the cylinder and the valve,from which it escapes by two pipes, placed opposite each other,with flanges for jointing them to the cylindrical part of the valve.The pipes at the other end slide on a vertical surface prepared forthem ; the motion is small, as the pipes are long, and the verticalmotion of the valve is not great. The valve is driven by twoeccentrics, one on each side of the cylinder, with rods taking pinsfitted to the top cast-iron ring. The steam cylinder is placedon the top of the blowing one, and is fitted with a common valve,with sufficient lap to cut off the steam at one-half of the stroke.The piston-rod crosshead is fitted with two connecting rods takingthe cranked shaft, the crosshead working in suitable guides. Two