SECT, ix.] OF STEAM ENGINES. 287 



In either case, 



when r is the radius of the axle, and R the radius of the wheels. 



The engines should work expansively when moving at the ordinary rate, and 

 upon the mean inclination, with the power of working at full pressure on the 

 steeper ascents. See Sect. v. art. 371 380. 



For further information respecting steam carriages and railways, see the 

 Appendix. 



