The Zoologist— January, 1870. 1955 



with roots, tufts of grass, leaves, and clay or mud. The branches of 

 the first tree are the perpendicular supports, almost all the remaining 

 sticks being placed horizontally and crosswise. The last six or eight 

 inches in height is very insecurely constructed, being nothing but 

 mud and leaves. The highest dam I ever saw was only about four 

 feet six inches; but the generality of them are not above two or three 

 feet. The action of the water, by bringing down mud, gravel or fallen 

 leaves, strengthens the dam by making a sloping bank against it ; and 

 the willow sticks of which it is composed sending forth their roots and 

 shoots, the dam in course of time becomes a fixture bound together 

 as strongly as well could be. The winter floods almost invariably 

 destroy the upper part of the dam, which is reconstructed afresh every 

 year. The shape of the dam is almost always semicircular, with the 

 crown of the arch down stream, thus reversing the order of things; 

 but I have no doubt this is in consequence of the heads of the first 

 or principal trees being floated down stream when they are first 

 thrown," 



Mr. Brown does not add much on this subject, but says, "The 

 dams here, as everywhere else, are perfectly constructed, and with an 

 opening in the middle for the current. * * * * Large trees are 

 universally felled so as to fall with the head to land, because, if 

 required for floating down, the branches would impede it being floated 

 off, while the difficulty of dragging it down is not so great, over and 

 above the fact of the impeding branches being easily gnawed off. 

 Much ingenuity is displayed to effect the fall of the tree in the proper 

 position. I have often, in my walks and sails along the solitary rivers 

 of the western wilds, seen three or four beavers piloting a large tree 

 down stream, and noticed that when they were approaching its desti- 

 nation they shoved it into the eddies inshore." 



My own experience differs, and in my notes I have thus expressed 

 myself: — "I must here correct what I take to be an error of some 

 authors, viz., that the beaver in making its dam usually selects a 

 situation where a tree by being cut down will fall across the brook, 

 and thereby greatly assist in damming, or, as it is termed in Newfound- 

 land, 'stenting' the water. To the closet naturalist and those 

 unable or unwilling to substantiate it, or prove otherwise, all this 

 reads very pretty and interesting, but to the practical naturalist it is a 

 mere fable, at least as far as my own experience goes, and that of the 

 many Indians and settlers that I have questioned on the si;bject : but 

 I will limit my observations to my own experience, which I think 



