176 FKAGMENTS OF SCIENCE. 



shows that serious changes have taken place since his 

 time. He describes it as 'a great and prodigious 

 cadence of water, to which the universe does not offer a 

 parallel.' The height of the fall, according to Hennepin, 

 was more than 600 feet. c The waters,' he says, ' which 

 fall from this great precipice do foam and boil in the 

 most astonishing manner, making a noise more terrible 

 than that of thunder. When the wind blows to the 

 south its frightful roaring may be heard for more than 

 fifteen leagues.' The Baron la Hontan, who visited 

 Niagara in 1687, makes the height 800 feet. In 1721 

 Charlevois, in a letter to Madame de Maintenon, after 

 referring to the exaggerations of his predecessors, thus 

 states the result of his own observations : e For my part, 

 after examining it on all sides, I am inclined to think 

 that we cannot allow it less than 140 or 150 feet,' a 

 remarkably close estimate. At that time, viz. a hundred 

 and fifty years ago, it had the shape of a horseshoe, and 

 reasons will subsequently be given for holding that this 

 has been always the form of the cataract, from its origin 

 to its present site. 



As regards the noise of the fall, Charlevois declares 

 the accounts of his predecessors, which, I may say, are 

 repeated to the present hour, to be altogether extrava- 

 gant. He is perfectly right. The thunders of Niagara 

 are formidable enough to those who really seek them 

 at the base of the Horseshoe Fall; but on the banks of 

 the river, and particularly above the fall, its silence, 

 rather than its noise, is surprising. This arises, in 

 part, from the lack of resonance ; the surrounding 

 country being flat, and therefore furnishing no echoing 

 surfaces to reinforce the shock of the water. The 

 resonance from the surrounding rocks causes the Swiss 

 Keuss at the Devil's Bridge, when full, to thunder more 

 loudly than the Niagara. 



