1 34 PR 'A QMENTS OF SCIENCE. 



is surprising. This arises, in part, from the lack of reso- 

 nance; 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 Reuss at the Devil's Bridge, when full, to 

 thunder more loudly than the Niagara. 



On Friday, November 1, 1872, just before reaching the 

 village of Niagara Falls, I caught, from the railway train, 

 my first glimpse of the smoke of the cataract. Immedi- 

 ately after my arrival I went with a friend to the northern 

 end of the American Fall. It may be that my mood at the 

 time toned down the impression produced by the first 

 aspect of this grand cascade; but I felt nothing like disap- 

 pointment, knowing, from old experience, that time and 

 close acquaintanceship, the gradual interweaving of mind 

 and nature, must powerfully influence my final estimate of 

 the scene. After dinner we crossed to Goat Island, and, 

 turning to the right, reached the southern end of the 

 American Fall. The river is here studded with small 

 islands. Crossing a wooden bridge to Luna Island, and 

 clasping a tree which grows near its edge, I looked long at 

 the cataract, which here shoots down the precipice like an 

 avalanche of foam. It grew in power and beauty. The chan- 

 nel spanned by the wooden bridge was deep, and the river 

 there doubled over the edge of the precipice, like the swell 

 of a muscle, unbroken. The ledge here overhangs, the 

 water being poured out far beyond the base of the precipice. 

 A space, called the Cave of the Winds, is thus enclosed 

 between the wall of ?'ock and the falling water. 



Goat Island ends in a sheer dry precipice, which con- 

 nects the American and Horseshoe Falls. Midway between 

 both is a wooden hut, the residence of the guide to the 

 Cave of the Winds, and from the hut a winding staircase, 

 culled Biddle's Stair, descends to the base of the precipice. 

 On the evening of my arrival I went down this stair, and 

 wandered along the bottom of the cliff. One well-known 

 factor in the formation and retreat of the cataract was 

 immediately observed. A thick layer of limestone formed the 

 upper portion of the cliff. This rested upon a bed of soft 

 shale, which extended round the base of the cataract. The 

 violent recoil of the water against this yielding substance 

 crumbles it away, undermining the ledge above, which, 

 unsupported, eventually breiks off, and produces the 

 observed recession. 



