^ British Association. 313 



fore, should consider that it would be a good thing to place watering- 

 pots before the wheels of the carriages, which would give an 

 additional power in the proportion of nearly 50 per cent. 



2. The next paper was on the application of our knowledge of 

 the phenomena of waves to the improvement of the navigation of 

 shallow rivers and canals. 



Mr. Russell, of Edinburgh, regretted he had not had time to put 

 his observations on this subject into writing. To gentlemen connected 

 with railways he would say, that where canals did exist there could 

 be no man who did not wish that the traffic upon them should be 

 conducted in the most favourable manner. The result of various 

 experiments he had made confirmed the law of Sir Isaac Newton, that 

 the resistance was in proportion to the square of the velocity. The 

 difference of resistance between a horse drawing a vessel trotting and 

 cantering was 108 to 130. 



He had made a table which was the result of 2400 experiments. 

 In going at a velocity of 



4 miles an hour the resistance was . . 33 lbs. 



6 91 



7i 265 



8^ 215 



9'' 235 



11 246 



12 352 



15 444 



But at the velocity of 20 miles an hour the vessel apparently sailed 

 along the surface of the water, and the resistance was very trifling. 

 They would observe that at 8^ miles an hour the resistance was not 

 so great as at 7 or 9. When a vessel was propelled at a certain 

 velocity and she stopped, it had t\\^ effect of giving an impetus to 

 the water, and produced a wave varying in its form according to the 

 mass of the water, and he had followed such a wave no less a dis- 

 tance than a mile and half; the velocity of the wave was uniform 

 and independent of the velocity of the vessel ; for if a vessel was 

 going 4 miles an hour the wave would go at the rate of 8 miles, and 

 he had seen a large wave overtake a small wave and pass it ; waves 

 never exceed in height the depth of the quiescent water. If the 

 velocity of a vessel did not exceed eight miles an hour, it did not 

 divide the water but pushed it forward in the shape of a wave, but 

 beyond that velocity the water was divided. It was possible to 

 increase the velocity and get upon the wave and then the resistance 

 was nothing. Where a canal had a depth of 



3 feet there might be a velocity of . . 6 miles an hour. 



5 8 



9 11 



So that the greater the depth of water the greater velocity might 

 be attained. The resistance was less above 6 miles an hour, but 4 

 and 6 miles an hour the velocity was unfavourable, beyond 11 miles 

 an hour you had high velocity and comparatively little resistance. 

 Where it was intended that the velocity should be great he recom- 



