EXPEDITION TO THE LAURENTIAN HILLS. 191 



convinced us that this practice of constantly changing the water 

 in our boots was not wise. A bootful that has been worked 

 in for some time becomes partially warm, and soon ceases to 

 be uncomfortable so far as temperature is concerned. In fact 

 it may be conceived of as a kind of stocking, protecting the 

 feet from the colder water outside, and not easily displaced by 

 what flows in at the top. To turn out this warm water, there- 

 fore, at every opportunity, and immediately take a charge of 

 cold water in its place, was a great waste of vital heat, which 

 we finally learned to avoid. Thus we came at last to work 

 right along without paying any special attention to our feet, 

 and found in pursuing this policy true economy of force every 

 way, and no ultimate damage to health. or comfort.*' 



The party also learned some other things on this voyage, 

 which the same writer reports as follows : 



" BEAVER DAMS. 



" Having opportunity for actual inspection of a great num- 

 ber of beaver dams, we got some new ideas about them. Bea- 

 vers do literally cut down trees and cut off logs. Their lower 

 front teeth are really chisels. We found one that had dropped 

 out, probably, from the jaw of a superannuated beaver. It 

 was a curved tusk, two or three inches long, and, instead of 

 being pointed, was beveled off at the end as accurately as 

 any chisel, and had a true-cutting edge of a quarter of an 

 inch in breadth. We saw many specimens of their work, 

 which, at a little distance, could hardly be distinguished from 

 axe-cuttings. Boys' hatchet-work would not compare with 

 them for smoothness. 



" But the idea that beavers build any thing like a common" 

 human dam namely, a regular log structure or stockade, ris- 

 ing with a steep, definite slope against the stream is a mis- 

 take. Their dams are simply huge deposits of sticks and 

 mud, mixed, and laid, apparently without much order, across 

 the stream. We saw none that raised the water more than 

 about a foot ; and sometimes the first notice we had of a dam 

 was from running our boat aground in what had appeared to 

 be deep and smooth water. Neither did we find any confir- 



