588 



SCIENCE 



[N. S. Vol. XXVII. No. 693 



to an unusual subject, by wbich the physical 

 features of the gorge were brought to light, 

 thus determining what work the Falls of 

 Niagara had accomplished at each point in 

 their recession. Apart from the soundings in 

 the vicinity of the crossing of the little 

 steamer Maid of the Mist, and at the canti- 

 lever bridge, none had been previously under- 

 taken, so that even the depth of the river and 

 its characteristics in front of the American 

 Falls, and nearer the Canadian Falls, as well 

 as in the gorge generally, were not known. 

 The whirlpool was a mystery, and it was 

 thought impossible to sound under the falls 

 themselves. 



For a mile and a half below the falls, the 

 soundings in the navigable basin were made 

 from the steamer Maid of the Mist, and from 

 the bridges. At the whirlpool and below, a 

 cable was extended across the gorge, and 

 soundings were made from it. Inside and 

 beyond the end of the gorge the soundings 

 were made from a small boat, as also in a 

 most dangerous section below the whirlpool. 

 As the currents were violent, resort was made 

 to self-registering hydrostatic tubes (the 

 Tanner-Blisch), so that the depths were ob- 

 tained. At the falls a suitably designed buoy 

 was used, in which were placed two separate 

 self-registering tubes. This was repeatedly 

 sent over the falls and recovered, so that re- 

 sults were obtained which were surprising. 

 In one instance the buoy struck the fallen 

 rock in the falls (as shown by the marks on 

 the lead shoe) at a depth of only 72 feet. In 

 the center of the river, farther down, the 

 depth was from 84 to 100 feet, but a lateral 

 channel reached 192 feet in depth. The ef- 

 fective excavating power is thus found to be 

 about 100 feet 'below the surface of the river. 

 The greater depth resulted from the previous 

 lower river surface. The line of deepest 

 soundings repeatedly showed 186 feet to near 

 the cantilever bridge, about two miles below 

 the falls. Under the bridge the maximum 

 depth is 85 feet (found by engineers for the 

 railway company). Here also borings had 

 been made beneath one of the piers, showing 

 a refilled channel to a depth of 185 feet. The 

 descent of the whirlpool rapids is 51.5 feet. 



A section across it shows a maximum depth 

 of 102 feet, but in the river course itself a 

 depth of 126 feet was obtained, but it is pos- 

 sible that one from 8 to 14 feet more may 

 occur just beyond. Thus, from near the falls 

 to the whirlpool, the floor of the canon is 

 found to reach 87-90 feet below the level of 

 Lake Ontario. 



Just below the whirlpool great changes oc- 

 cur in the gorge, and at a quarter of a mile 

 farther the maximum depth was found to be 

 99 feet, or to a plane 59 feet below the level 

 of Lake Ontario. As the Whirlpool Eapids 

 are produced by the fallen rocks refilling the 

 original channel, so also Foster Rapids are 

 due to the same cause. Other measurements 

 were made. Those a short distance within 

 the gorge were found to reach 150 feet, and 

 others some distance beyond its termination 

 showed a narrow inner channel to a depth of 

 183 feet, or 181 feet below the level of Lake 

 Ontario. These discoveries were hitherto ab- 

 solutely unsuspected. 



These results show that the narrow channel 

 was formed when the level of Lake Ontario 

 was about 180 feet lower than now, at the 

 time when the Niagara was draining only the 

 Erie basin and not the four Upper Great 

 Lakes. They show that the falls were once 

 very much higher than now, and that the last 

 cataract, of the three which composed them, 

 was alone over 300 feet high, and the whole 

 aggregated over 500 feet. 



The soundings also complete the proof that 

 the falls were located just above Foster Flats, 

 or about three miles within the end of the 

 gorge, when the volume of the Niagara was 

 vastly augmented, owing to the addition of 

 the waters from the three highest lakes, which 

 now took place. Again, the soundings at the 

 falls bring to light the fact that the modern 

 cataract is not so high as it was a few hun- 

 dred years ago, before the completion of the 

 Whirlpool Eapids. 



These investigations were made under com- 

 mission of Dr. Eobert Bell, the head of the 

 Geological Survey of Canada. 



A full discussion of the important signifi- 

 cance of these results is soon to be published 



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