HYDROLOGY OF NEW YORK 



357 



We have, then, a total area of the basin of 8360 square miles. 1 

 The rainfall of this catchment is stated in the Report of the 

 Board of Engineers on Deep Waterways at an average of about 

 33 inches per year. But table Xo. 25 shows that for the 12 years 

 from 1891 to 1902, inclusive, the rainfall of Champlain valley was 

 37.06 inches. 



The lake is considered as terminating on the south at White- 

 hall and on the north at St Johns, on Richelieu river. The low- 

 water elevation is 95.03 feet + T. W. and the high water, 103.78 

 feet + T. W. The length is 125 miles from Whitehall to St 

 Johns, and the breadth 13 miles. The outlet of Lake Champlain 

 is Richelieu river, which flows northerly across the Province of 

 Quebec, entering the St Lawrence at Sorel. The length of the 

 river is 75 miles. It receiYes from New York the drainage from 

 the northeast slope of the Adirondacks, amounting to 35 per 

 cent of the whole. A record of the elevation of lake surface at 

 Rouses Point has been kept by the United States Corps of Engi- 

 neers since 1875. 



In 1896 the construction of a power plant at Chambly was 

 begun by the Royal Electric Company of Montreal. The dam is 

 of concrete masonry, strengthened with imbedded iron bars. 

 The hight from apron to crest is 18 feet, affording a fall of 28 

 feet at the power-house. A calibration curve of Richelieu river 

 was constructed by the Board of Engineers on Deep Waterways 

 by comparing the computed discharge over this dam with the 

 corresponding stage of Lake Champlain at Fort Montgomery, 

 and taking into consideration the slope of Richelieu riYer in the 

 intervening distance of thirty-five miles. The discharge in cubic 

 feet per second has been deduced from this curve. 



The record of Lake Champlain is giYen not only because it is 

 computed over a dam, but because it is a long record, although in 

 the following tables it has only been taken from 1880-1902, in- 

 clusive. The catchment area of 7750 square miles, as given by 

 the Board of Engineers on Deep Waterways, is placed at the 

 head of the tables. 



iThe preceding figures are derived from the Report of the United States 

 Deep Waterways Commission (1896). The Board of Engineers on Deep 

 Waterways gave the area of Lake Champlain at 437 square miles and the 

 total area of the catchment at 7,750 square miles. 



