196 . THE AMERICAN BEAVER. 



and hold the surface water from rains, as well as that 

 passed down by drainage from the high grounds, after 

 which it was collected by filtration, in the channel of 

 the canal which is sunk about three feet below the level 

 of the surrounding ground. At the distance of forty- 

 seven feet from the second, there is a third and much 

 larger dam, one hundred and forty-two feet long, con- 

 structed in a semicircle, with its arms pointing out 

 toward the high ground, and designed for the same 

 object. It collects the surface water in pools, here 

 and there, but fails to form a pond for want of suffi- 

 cient water. , With this dam the canal terminates. 

 At this point the hard wood is reached, at the dis- 

 tance of five hundred and twenty-three feet from the 

 pond. A B in the diagram represent a transverse 

 section of the first dam, on the line of the canal; and 

 C D, the same of the third. The crests of these 

 dams where they cross the canal are depressed, or 

 worn down, in the centre, by the constant passage of 

 beavers over them while going to and fro, and dragging 

 their cuttings. This canal, with its adjuncts of dams 

 and its manifest objects, is a remarkable work, tran- 

 scending very much the ordinary estimates of the in- 

 telligence of the beaver. It served to bring the occu- 

 pants of the pond into easy connection, by water, with 

 the trees that supplied them with food, as well as to 

 relieve them from the tedious, and perhaps impossible, 

 task of moving their cuttings five hundred feet over 

 uneven ground, unassisted by any descent. As an 

 effort of free intelligence to surmount natural obstacles, 

 it is one of the highest achievements of this animal. 

 The width and depth of the channel at different 

 points are sufficiently shown upon the ground plan. 



