84 SCIENCE OF SUCCESSFUL, THRESHING 



Dividing by 10,000,000, or pointing off seven places, 

 we get 47.4=brake horse-power. 



Compounded Engines. A compounded engine is one 

 in which the steam is expanded in two or more cylinders. 

 Threshing engines, when compounded, are "two-cylinder" 

 compounds, but large stationary and marine engines are 

 often "triple" and sometimes "quadruple" expansion. 



FIG. 24. SECTIONAL VIEW OF "WOOLF" COMPOUNDED CYLINDER. 



There are different types of two-cylinder compounds, viz. : 

 the "cross," where the cylinders are abreast and each 

 piston connected to a separate crank ; the "trunk," in which 

 two pistons of the same size are connected by an enlarged 

 rod or trunk, the high-pressure cylinder being in the form 

 of an annular ring between the pistons, and the low- 

 pressure at the ends of the long cylinder which is the same 



