Engineers 



When the latter are three years old they forsake their family 

 home and set up housekeeping on their own account. 

 Sometimes, however, the village becomes overcrowded ; 

 then the older members of the community migrate to 

 another spot, leaving the youngsters in sole possession of 

 the abandoned huts. 



The engineering proclivities of the beavers are directed 

 to the building of huts, or lodges, as they are termed, and 

 to the construction of dams. The lodges are of three 

 kinds, according to their situation, but, in general, they 

 may be considered as dome-shaped coverings to one end 

 of their burrows. The dams hold back the water of the 

 streams in whose vicinity the lodges are built, and there 

 is good reason for their construction, as we shall show 

 later, quite apart from the fact that the beaver always 

 prefers swimming in water to walking on land, so much 

 so that water is an absolute necessity for him. 



The building of the beaver's dam is one of the most in- 

 genious performances in the whole of the animal kingdom. 

 In the first place, trees must be felled, and the beaver is no 

 mean woodman. Provided with chisel-like teeth^ he has 

 no difficulty in gnawing the hardest wood, and this he 

 proceeds to do by sitting on his haunches and cutting a 

 deep groove right round the tree. As he gnaws the groove 

 deeper and deeper, so he widens it, till, eventually, the tree 

 is given a waist. This stage of the operations is an 

 anxious one for the beaver and the subject of considerable 

 thought. He has no wish to be injured by the falling tree. 

 With wonderful instinct he divines on which side the tree 

 is likely to fall, so, from the safe side, he gives a few deep 

 bites and the tree is felled. 



When once this part of the work is completed the 

 beaver loses no time in cutting the timber into logs about 

 a yard in length, gnawing the wood just as he did when 

 felling the tree, with the result that the logs, when cut, 

 have rounded or almost pointed ends. All these logs are 

 used in the construction of the dam, and the design of this 



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