462 POPULAR LECTURES AND ADDRESSES. 



the way of work ? that the procession once 

 formed will go on of itself, requiring no work 

 to sustain it ? Here is the explanation. The 

 procession has an end. The canal may be 

 infinitely long, the time the boat may be 

 going may be as long as you please; but let 

 us think of a beginning the boat started, the 

 procession began to form. The next time you 

 make a passage in a steamer, especially in smooth 

 water, look behind the steamer, and you will 

 see a wave or two as the steamer gets into motion. 

 As it goes faster and faster, you will see a 

 wave-pattern spread out; and if you were on 

 shore, or in a boat in the wake of the steamer, 

 you would see that the rear end of the procession 

 of waves follows the steamer at an increasing 

 distance behind. It is an exceedingly complicated 

 phenomenon, and it would take a great deal of 

 study to make out the law of it merely from 

 observation. In a canal the thing is more simple. 

 Scott Russell however did not include this in 

 his work. This was left to Stokes, to Osborne 

 Reynolds, and to Lord Rayleigh. The velocity 



