﻿Jan., 1857.] 



ELLIOTT SOCIETY. 



97 



of circuit of brink, but from greater depth of water, and possi- 

 bly, also, from greater velocity. As both Falls draw their waters 

 from the same source above the eastern end of Goat Island, and 

 the brink of the Canadian Fall is 8 feet lower than that of the 

 American Fall, the velocity at the former must be greater than at 

 the latter, (other things being equal), but in what ratio is unknown. 

 It has been reported that the hull of a vessel 16 feet from deck to 

 keel was sent over the Canada Fall, that the deck was level with 

 the water at the time of passing over the brink, and that the keel 

 met with no obstruction in its passage at that point of the brink; 

 it may be hence inferred, that the depth of water at this Fall is at 

 least 20 feet. The whole height of this Fall is 158 feet I have 

 been behind the sheet of water at this Fall, and proceeded some dis- 

 tance along the ledge of rock which forms the foot-hold of the ad- 

 venturous visitor, but can form no reliable estimate of the height 

 ef the under-surface - of the sheet of water over head; it can 

 scarcely be less than 58 feet, leaving 100 feet as the utmost possi- 

 ble depth of water at the brink of the Fail. 



Now, if for the American Fall, we suppose a depth of 10 feet, 

 (which does not appear to us too great,) to give at the Canada Fall 

 a volume 15 times as great to each linear } T ard of brink, would 

 require a depth of 150 feet, almost equal to the whole height of 

 the Fall; or if we suppose for the Canada Fall the maximum 

 depth 100 feet, for the ratio of recess of the two Falls the minimum 

 value 1 to 15, it would require a depth of a little less than 7 feet 

 at the American Fall to make the volumes proportional to the rates 

 of recess, and this value appears to us to be near the minimum 

 depth to be assigned to the American Fall. As these numbers are 

 all taken on the verge of probabilities, it would appear that the 

 most probable ratio of volumes, even if the effect due to difference 

 of velocity be included, is less than that of the ratio ef recess. In 

 such case we shall be compelled to look to the two remaining causes 

 for the explanation of the difference, unless we suppose the me- 

 chanical effect, the abruption of the rock, as a complex result, to 

 be proportioned not to the volumes simply, but to some undeter- 

 mined higher power of the volumes, or to the product of the volume 

 by some undetermined like power of the velocity. 



The hypothesis next presented above, does not appear in itself 

 to be a very probable one, I can at present see no reason why 

 there should be a greater or less facility of abruption in one direc- 

 II 



