THE LOCOMOTIVE. 



the machinery of the engine must perform in order to accomplish 

 such effects. 



Let us take the example, not uncommon, of a train of coaches 



\ 



Fig, 10. 



carried upon a railway, at a rate of sixty miles per hour. Assum- 

 ing, as in a former example, that the circumference of the driving 

 wheel measures 26^ feet, these wheels, as already explained, will 

 revolve one hundred times in passing over half a mile, and there- 

 130 



