362 



THE STEAM-ENGINE. 





The eccentric turns within a collar, which is fastened to 

 the frame T. Every turn of the shaft moves the eccentric 

 with its collar and the frame T, backward and forward into 

 the two positions indicated by the full and dotted lines of 



FIG. 268. 



Fig. 268. The point a may be fastened directly to the 

 sliding-valve rod or through the agency of the bent lever 

 abc, as the circumstances of the case render more desirable. 



574. The Governor and Fly- Wheel. The 



admission of steam through M (Fig. 267) is regulated by a 

 throttle-valve worked by a governor (Fig. 269). A vertical 

 shaft is given a rotary motion by the machinery. To the 

 top of this rod are hinged two arms carrying heavy balls, lb. 

 From these arms, supports extend to a 

 collar, c, surrounding the vertical rod. 

 This collar is connected with a valve con- 

 trolling the admission of steam to the 

 valve-chest in such a way that when the 

 collar rises the valve closes. As the 

 machinery increases its speed, the balls 

 revolve more rapidly about the vertical 

 axis and tend to fly further apart ( 74). 

 In doing so, they raise the collar and partly close the valve, 

 diminishing the supply of steam. The machinery is thus 

 made to slacken its speed, the balls fall, and the valve opens. 

 The rapidity of motion can therefore be confined within 



FIG. 269. 



