CATALOG OF THE MECHANICAL COLLECTIONS 75 



the action of the coiled spring. A slide on the governor, which is 

 operated from the crankshaft, carries an inclined block that registers 

 with the hooked connecting rod, depresses it against the action of the 

 flat spring, and releases it from the reciprocating block. The time 

 at which the valve is released depends upon the position of the in- 

 clined block, which, in turn, depends upon the position of the governor 

 balls and finally upon the speed of the engine. 



CORLISS PRESSURE REGULATOR, 1869 



U.S.N.M. no. 309236 ; original patent model ; transferred from the United States 

 Patent OfBce ; not illustrated. 



This model was submitted with the application for the patent 

 issued to George H. Corliss, of Providence, R. I., January 5, 1869, no. 

 85566. 



The model represents a device for the automatic reduction of the 

 pressure of steam when it is to be used for heating or any other pur- 

 pose requiring steam at less than boiler pressure. 



The device consists of a flat-sided circular chamber to which the 

 steam at high pressure is admitted. At the center of one side of 

 the chamber is a connecting space from which the low-pressure steam 

 is taken. The passage between the chamber and the space is closed 

 by a conical valve, the seat of which is formed in the side of the 

 chamber and the valve disk of which is supported on a post fixed 

 to the center of the other side of the chamber. The valve closes 

 inward, so that spreading the two sides of the chamber will tend 

 to close the valve. As the pressure of steam within the chamber tends 

 to spread the sides of the chamber, an increase in the higher steam 

 pressure will diminish the valve opening and thus diminish the flow 

 of steam. By proper adjustment and proportioning of the valve 

 area the regulator should maintain a constant pressure in the low- 

 pressure space. 



CORLISS COMPOUND BEAM PUMPING ENGINE, 1870 



PLATK 18, FiGUBE 1 



U.S.N.M. no. 309820; model; gift of the Franklin Machine Co.; photograph 

 no. 18114. 



This is a model (1/10 actual size) of a large, vertical, 2-cylinder, 

 compound beam engine operating four pump cylinders of the city- 

 waterworks type. The model was made at the original Corliss En- 

 gine Works at Providence, R. I., during the lifetime of George H. 

 Corliss. 



The engine consists of one high-pressure and one low-pressure ver- 

 tical cylinder, each equipped with the simple Corliss valve gear. 

 Upon each cylinder is a skeleton cylindrical column in which are cast 

 the cross-head guides. From each cross head the connecting rod goes 



