THE BEAVER. 413 



logs are rounded and rather pointed, as may be seen by reference 

 to the illustration. In the Zoological Gardens may be seen 

 many excellent examples of timber which has been cut by the 

 Beaver : the logs and cut stumps which are given in the illustra- 

 tion were sketched from those objects. 



The next part of the task is, to make these logs into a dam. 

 Now, whereas some persons have endeavoured to make the 

 Beaver a more ingenious animal than it really is, and have 

 accredited it with powers which only belong to mankind, others 

 have gone to the other extreme, and have denied the existence 

 of a regularly built dam, saying that it is entirely accidental, 

 and caused by the logs that are washed down by the stream, 

 after the Beavers have nibbled off all the bark. 



That this position is untenable is evident from the acknow- 

 ledged fact that the dam is by no means placed at random in the 

 stream, just where a few logs may have happened to lodge, but 

 is set exactly where it is wanted, and is made so as to suit the 

 force of the current. In those places where the stream runs 

 slowly, the dam is carried straight across the river, but in those 

 where the water has much power, the barrier is made in a 

 convex shape, so as to resist the force of the rushing water. 

 The power of the stream can, therefore, always he inferred from 

 the shape of the dam which the Beavers have built across it. 



Some of these dams are of very great size, measuring two or 

 three hundred yards in length, and ten or twelve feet in thickness, 

 and their form exactly corresponds ^vith the force of the stream, 

 being straight in some parts, and more or less convex in others. 



The dam is formed, not by forcing the ends of the logs into 

 the bed of the river, but by laying them horizontally, and covering 

 them with stones and earth until they can resist the force of the 

 water. Vast numbers of logs are thus laid, and as fast as the 

 water rises, fresh materials are added, being obtained mostly 

 from the trunks and branches of trees which have been stripped 

 of their bark by the Beavers. 



The reader will remember that many persons have thought 

 that the dam of the Beaver is only an accidental agglomeration 

 of loose logs and branches, without any engineering skill on the 

 part of the animals. There is some truth in this statement, 

 though the assertion is too sweeping. For, after the Beavers 

 have completed their dam, it obstructs the course of the stream 



