CATALOG OF THE MECHANICAL COLLECTIONS 53 



is usual in these engines is employed. The valve is an oscillating 

 valve operated from an eccentric on the shaft. The cross head does 

 not have sliding faces but is guided by rollers attached to the cross 

 head by pins. These rollers turn over one complete turn and back 

 in each cycle of the piston. 



FISKE OSCILLATING ENGINE, 1880 



U.S.N.M. no. 308712 ; original patent model ; transferred from the United States 

 Patent Office ; not illustrated. 



This model was submitted with the application for the patent issued 

 to William S. Fiske, of Stamford, Conn., August 24, 1880, no. 231551. 



The model represents a vertical steam engine with an oscillating 

 cylinder, circular slide valve, and hollow cylinder trunnions for the 

 admission and exhaust of steam. Steam is admitted to the center of 

 the annular valve through the adjacent trunnion. The exhaust is 

 conveyed from the valve seat around the cylmder in a hollow band 

 cast on the cylinder for that purpose and leaves the engine through 

 the opposite trunnion. The valve is driven by an eccentric on the 

 shaft. The valve rod is provided with a cross head moving in a 

 guide on the cylinder and oscillating with it. The eccentric rod 

 carries a pin that slides in a curved slot in the cross head and produces 

 an even motion of the valve thereby. 



MARINE WALKING BEAM STEAM ENGINE, 1888 



U.S.N.M. no. 310311 ; model ; gift of Andrew L. Weis ; not illustrated. 



The model represents a typical American river paddle-wheel steam- 

 boat engine of the late nineteenth century. A piston operating in a 

 vertical steam cylinder works upon one end of a walking beam over- 

 head, while a long connecting rod works from the other end of the 

 beam directly upon the crank in the paddle-wheel shaft. The model 

 was made by Frank N. Weis, an assistant engineer on the Maumee 

 River steamboat Chief Justice Waite and is presumed to represent the 

 engine of that boat. 



The beam of the engine is supported between bearings at the tops 

 of two tall cast-iron A-frames, which in the steamboat would rest 

 directly upon box-girder keelsons in the hull. The steam cylinder 

 stands between the forward legs of the A-frames. Forward of the 

 cylinder are two columnar pipes bolted to horizontal valve chests 

 above and below, which join the pipes but are not connecting. Each 

 valve chest is divided at the center so that one pipe and its side of 

 both the upper and lower valve chest form the steam-supply passage, 

 while the other pipe and its side of the valve chests form the exhaust 

 passage connected to the condenser located below and aft of the 

 cvlinder. 



