IT seems to have been a matter of common observation among the early colonists of America that the Niagara Falls had receded from the escarpment at Queenston to their present position six miles up the gorge. In spite of the view then frequently held that ravines were to be accounted for by violent rendings of the crust, those six miles, even in the eighteenth century, were appealed to as a natural time-scale. It was, moreover, felt that the rate of recession might give us a measure of the antiquity of the earth. James Hall in 1842 established a series of marks and monuments to which subsequent surveys might refer, and Mr. G. K. Gilbert 1 now draws conclusions from the work of his predecessors in 1842, 1875, 1886, and 1890, and from Mr. W. C. Hall's re-examination of the edge for the United States Geological Survey in 1905. He reproduces some of Captain Basil Hall's drawings, made with a camera lucida fl 1827, and interesting photographs taken from 1855 onward. The former, which appear to be of great accuracy, throw doubt on certain details of the map of 1842. Mr. Gilbert regards the survey of 1905 as of especial importance, since it is the last record of the Niagara River in a natural condition. “The Erie Canal is supplied with water from the Niagara River at Buffalo, the Welland Canal is supplied from Lake Erie, and the Chicago Drainage Canal draws water from Lake Michigan. All the water thus diverted is withdrawn from the cataract. So also is the water diverted from the river above the falls for factory purposes and for use in the generation of electricity “(p. 12).