THE EXPERIMENTS OF 1834. 83 



wave, and at another one-fourth part greater than the said velocity, both of these 

 objects wUl be attained. 



When a canal is to be constructed for a given kind of transport, such a depth 

 ought to be selected as will admit of those velocities above and below the wave, 

 which are required for the trade of the canal, the velocity of the wave being as 

 far removed as possible from the velocities below it and above it. 



When vessels only of a small draught of water are required for the trade, 

 the canal should be as shallow as possible, and when larger vessels are desirable, 

 the depth should be increased as much as possible, so as to remove the wave to 

 a distance beyond the velocity of the motion of the vessels, and prevent anterior 

 accimiulation. 



The breadth of the canal materially affects the resistance produced by the 

 wave, although it does not du'ectly aflFect its velocity. By preventing the diffu- 

 sion of the wave, the narrowness of the canal increases the height of it, in conse- 

 quence of which the resistance to the lower velocities is augmented, and facilita- 

 tion in the higher velocities increased. But in general the depth is of much 

 more consequence than the breadth of the canal, as the retardation or facihtation 

 produced by the vicinity of the wave, is a quantity which may be made to bear 

 an almost infinite ratio to the other elements of resistance. 



For slow velocities alone, a broad and deep canal, but especially deep, should 

 be made ; and for high velocities, a narrow and shallow one, especially shallow, 

 that the range of velocities may be extensive, and the velocity at which the wave 

 is to overcome small. 



There are also certain relations to be observed between the velocity of the 

 wave, and the dimensions of the vessels of easiest transport, also between the 

 form of the vessel and that of the wave; but this is an inquiry which I have not 

 yet completed, but hope soon to terminate successfully. Relations have been 

 distinctly indicated, but not accurately defined. 



It is perhaps worthy of remark, that a vessel on the summit of the wave is 

 more easily directed by the hehn, than when behind it. In the latter case, the 

 vessel by her anterior immersion is prevented from answering the helm, while in 

 the former case, this obstruction being diminished, and the displaced fluid collect- 

 ed around the centre of gravity, horizontal rotation on the vertical axis passing 

 through the centre of gravity is less resisted by the fluid than formerly, in pro- 

 portion as the third power of their present distance from the particles of the 

 wave is less than the third power of their former distance from the centre of ro- 

 tation. 



Another circumstance stiU more curious than the foregoing is, that at the 

 instant of passing one another at high velocities, vessels are much more deli- 



