[Illustration: FIG. 1. DIA. OF CYLINDER = 40'' STROKE = 10 ft. REVS = 41 SCALE OF DIAGRAMS 40 LBS = 1 INCH FIG. 2.] We illustrate one of the largest Corliss engines ever constructed. It is of the single cylinder, horizontal, condensing type, with one cylinder 40 inches diameter, and 10 feet stroke, and makes forty-five revolutions per minute, corresponding to a piston speed of 900 feet per minute. At mid stroke the velocity of the piston is 1,402 feet per minute nearly, and its energy in foot pounds amounts to about 8.6 times its weight. The cylinder is steam jacketed on the body and ends, and is fitted with Corliss valves and Inglis & Spencer's automatic Corliss valve expansion gear. Referring to the general drawing of the engine, it will be seen that the cylinder is bolted directly to the end of the massive cast iron frame, and the piston coupled direct to the crank by the steel piston rod and crosshead and the connecting rod. The connecting rod is 28 feet long center to center, and 12 inches diameter at the middle. The crankshaft is made of forged Bolton steel, and is 21 inches diameter at the part where the fly-wheel is carried. The fly driving wheel is 35 feet in diameter, and grooved for twenty-seven ropes, which transmit the power direct to the various line shafts in the mill. The rope grooves are made on Hick, Hargreaves & Co.'s standard pattern of deep groove, and the wheel, which is built up, is constructed on their improved plan with separate arms and boss, and twelve segments in the rim with joints planed to the true angle by a special machine designed and made by themselves. The weight of the fly-wheel is about 60 tons. The condensing apparatus is arranged below, so that there is complete drainage from the cylinder to the condenser. The air pump, which is 36 inches diameter and 2 feet 6 inches stroke, is a vertical pump worked by wrought iron plate levers and two side links, shown by dotted lines, from the main crosshead. The engine is fenced off by neat railing, and a platform with access from one side is fitted round the top of the cylinder for getting conveniently to the valve spindles and lubricators. The above engraving, which is a side elevation of the cylinder, shows the valve gear complete. There are two central disk plates worked by separate eccentrics, which give separate motion to the steam and exhaust valves. The eccentrics are mounted on a small cross shaft, which is driven by a line shaft and gear wheels. The piston rod passes out at the back end of the cylinder and is carried by a shoe slide and guide bar, as shown more fully in the detailed sectional elevation through the cylinder, showing also the covers and jackets in section. The cylinder, made in four pieces, is built up on Mr. W. Inglis's patent arrangement, with separate liner and steam jacket casing and separate end valve chambers. This arrangement simplifies the castings and secures good and sound ones. The