IN THE NORTH A ME U I C A N L A K E S. 3 



Since 183S, reliable measurements have greatly increased. That which I have 

 given for Lake Erie is an abstract of the registers at three ports — one at each end 

 of the Lake, and one near the middle or widest part. 



At Detroit, Messrs. A. E. Hathan and S. W. Higgins made use of the base of 

 the hydraulic tower connected with the water-works of that city as a bench mark, 

 counting downwards to the surface of the water in the river. At Cleveland the 

 liigh water line of June, 1838, has been used as zero, also reckoning downwards. 

 This line was two feet below the surface of the cast pier, at the south end of the 

 steps leading up the parapet wall. The mitre sill of the guard lock at Black Rock 

 was at first used by the engineers of the State of New York on which to register 

 the depth of water. When the enlargement of the Erie Canal was commenced, 

 Mr. John Lothrop, C. E., transferred the measurements to the bottom of the canal, 

 at Buffalo, which is one foot below the mitre sill of the guard lock. (See Plate I., 

 No. 1.) 



As the records at different places are but seldom of the same dates, it is not easy 

 to bring them into comparison with each other. To effect this, in the only manner 

 they admit of, I neglect the descent of the Detroit River from that city to the Lake, 

 and regard the surface of the Lake as level. The longest period of the Detroit 

 tables, which correspond with those at Cleveland, was compared by the mean of 

 both, which gave the elevation of the stone water table of the hydraulic tower 

 above the Cleveland zero at three feet iVo ths- By Mr. Hathan's register this mark 

 was, in June, 1838, three feet ^Vot'^^ above the surface of the river. 



During the month of July, 1851, Mr. Lothrop, at Buffalo, and I myself, at Cleve- 

 land, kept registers. The fluctuations of this month were small, the weather being 

 very calm. The high water line of June, 1838, by this comparison, corresponds to 

 a depth of water in the enlarged canal of eleven feet yVo^^^- The base of the 

 hydraulic tower is, therefore, fourteen feet yVij^lis above the bottom of canal. 



