CATALOG OF THE MECHANICAL COLLECTIONS 71 



on the valve seats. The valves are long narrow gridiron valves, 

 ■which reciprocate in the direction parallel to the axis of the plug. 

 They are actuated by rods and slides and roller cams, which are 

 actuated by curved slots in a collar, which, in turn, is rocked by a 

 rock shaft on the collar. The steam valve slide has a disengaging 

 pawl to provide an adjustable cut-off. 



ADDITIONAL STEAM-ENGINE VALVE GEARS IN THE COLLECTION, 

 NOT OTHERWISE DESCRIBED 



Cut-off, Thomas Rogers, patented in 1845, Patent Otfice model, transferred 

 from the United States Patent Office. U.S.N.M. no. 308642. 



Valve action, patented by Sulzer Brothers, Patent Office model, transferred 

 from the United States Patent Office. U.S.N.M. no. 308729. 



Adjustable eccentrics on a common shaft, Patent Office model. Patent no. 

 46278, issued to J. M. Stone February 7, 1865. Transfer from the United 

 States Patent Office. U.S.N.M. no. 309249. 



INVENTIONS OF GEORGE H. CORLISS 



CORLISS DROP CUT-OFF VAL\'E GEAR, 1849 



Plate 17, Figure 2 



U.S.N.M. no. 308646 ; original patent model ; transferred from the United States 

 Patent Office ; photograph no. 31694. 



This model was submitted with the application for the patent issued 

 to George H. Corliss, of Providence, R.^L, March 10, 1849, no. 6162; 

 reissued May 18, 1851, no. 200. 



This is considered the first variable cut-off valve gear in which the 

 point of the cut-off is determined by the engine governor. The patent 

 was the first issued to George H. Corliss for steam engine improve- 

 ments and the model represents the original form of the Corliss steam 

 engine. 



The engine represented by the model consists of a heavy horizontal 

 bed at one end of which is a large, vertical, double-acting cylinder, 

 at the other the bearings in which a crankshaft and large flywheel 

 turn. At the center of the bed two columns carry the bearings of a 

 horizontal rocking beam. Both columns and the beam are castings 

 combined with tension rods in a manner covered by the patent. The 

 valves of the engine, the flat slide type, are arranged above and below 

 the top and bottom of the cylinder in steam chests. A separate steam 

 and exhaust valve is provided at each end of the cylinder. All four 

 valves are operated from a wrist plate or disk, which is oscillated by 

 one eccentric on the crankshaft. Four rods connect the wrist plate 

 with rocking levers or bell cranks, which, in turn, are connected to 

 the valve rods. The rods of the exhaust valves are permanently con- 

 nected to their individual rock levers, which move the valves as the 

 wrist plate is oscillated. The steam valves are connected in a similar 



