880 NEW YORK STATE MUSEUM 



m 



4) The growth of aquatic plants on long levels and the forma- 

 tion of sand bars in the canal, which have tended to decrease the 

 amount passing. 



Among minor sources of loss, evaporation and absorption by 

 growing plants may be mentioned, both of which vary somewhat 

 in different years, although neither can be considered a serious 

 source of loss. 



A study of all the measurements in detail shows that in an 

 artificial channel of the dimensions of the original Erie canal, 

 there should be provided at least 1.33 to 1.67 cubic feet per 

 second per mile, exclusive of water for filling and for lockages. 



Using the data of the measurements of 1841, Mr Childs arrived 

 at the water supply of the enlarged canal of that day in the fol- 

 lowing manner: It was assumed that the loss by filtration 

 through the bottom and sides of the canal would be as the square 

 root of the pressure or depth of the water, and as the area of the 

 surface pressed. Proceeding on this assumption, he computed 

 the quantity required to supply the losses from filtration, leakage, 

 and evaporation (in the enlarged canal, 1840 to 1860), at 3.17 

 cubic feet per second per mile. This figure was subsequently 

 substantially adopted for the entire enlarged canal, and, with the 

 exception of a few special cases is still in use. 



Adding the amount required for lockages at lock 53, Mr Childs 

 placed the entire supply for the western division, from Lockport 

 to the east end, at 3.48 cubic feet per second per mile, or at a 

 total of 424 cubic feet per second for 122 miles of canal. 



The canal enlargement of 1895 contemplated an increase in 

 depth from 7 to 9 feet. Taking into account the results of the 

 measurements on the original Erie canal, as well as those made 

 by Mr Childs on the enlarged canal of 1840 to 1860, it has been 

 concluded that the proper figure for water supply on the western 

 division, to which the studies thus far specially refer, should be 

 taken at from 4.17 to 4.50 cubic feet per second per mile. 1 



ir rhe foregoing statements in regard to measurements of water supply of 

 Erie canal are abstracted from tteport on the Water Supply of the Western 

 Division of the Erie Canal, by the writer, and are to he found in Appenidx I 

 to the An. Kept of the State Engineer and Surveyor for the fiscal year 

 ending September 30, 189G. 



