THE BEAVER 



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mous dimensions. It is not at all unusual for a single dam to be 

 two hundred yards in length, fifteen or sixteen feet wide at the 

 bottom, five feet in width at the top, and from ten to twelve feet 

 in height. Such a dam as this, of course, is the work of several 

 years, and the beavers are always busy both in adding to it, 

 and in repairing any damage which it may chance to have sus- 

 tained. 



When the current of the stream is rapid, the beavers appear 

 to know that a straight dam will almost certainly be washed 



Beaver 



away. They therefore build the barrier in the torm of a curve, 

 with the convex side presented to the current, the force of which 

 is thus broken, and diverted to either side. 



As time goes on, the completed dam becomes greatly enlarged 

 by the fallen trees, branches, &c., which float up against it. 

 After a time earth is deposited upon it, and vegetation springs 

 up, until a broad bank of herbage extends from side to side of 

 the river. 



The dams greatly change the appearance, not only of the 

 river itself, but also of the surrounding country; for the constant 

 labours of the busy little animals of course result in the formation 

 of clearings in forest-land, which are often of many acres in extent. 

 On these, which are partially flooded during a considerable portion 



(M868) 



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