MAMMALIA — BEAVER. 225 



At a short distance above a beaver dam, the number of trees which have 

 been cut down, appears truly surprising, and the regularity of the stumps 

 which are left, might lead persons unacquainted with the habits of the 

 animal to believe that the clearing was the result of human industry. 



"The figure of the dam varies according to circumstances. Should the 

 current be very gentle, the dam is carried nearly straight across ; but when 

 the stream is swiftly flowing, it is uniformly made with a considerable 

 curve, having the convex part opposed to the current. Along with the 

 trunks and branches of trees, they intermingle mud and stones, to give 

 greater security ; and when dams have been long undisturbed and frequently 

 repaired, they acquire great solidity, and their power of resisting the pres- 

 sure of water and ice, is greatly increased by the willow, birch, &c, occa- 

 sionally taking root, and eventually growing up into something of a 

 regular hedge. The materials used in constructing the dams, are secured 

 solely by the resting of the branches, &c, against the bottom, and the sub- 

 sequent accumulation of mud and stones, by the force of the stream, or by 

 the industry of the beavers. 



" The dwellings of the beaver are formed of the same materials as their 

 dams, and are very rude, though strong, and adapted in size to the number 

 of their inhabitants. These are seldom more than four old, and six or eight 

 young ones. Double that number have been occasionally found in one of 

 the lodges, though this is by no means a very common occurrence. 



"When building their houses, they place most of the wood cross-wise, and 

 nearly horizontally, observing no other order than that of leaving a cavity in 

 the middle. Branches, which project inward, are cut off with their teeth and 

 thrown among the rest. The houses are by no means built of sticks first, 

 and then plastered, but all the materials, sticks, mud, and stones, if the 

 latter can be procured, are mixed up together, and this composition is 

 employed from the foundation to the summit. The mud is obtained from 

 the adjacent banks or bottom of the stream or pond, near the door of the 

 hut. Mud and stones, the beaver always carries, by holding them between 

 his fore paws and throat. 



" Their work is all performed at night, and with much expedition. When 

 straw or grass is mingled with the mud used by them in building, it is an 

 accidental circumstance, owing to the nature of the spot, whence the latter 

 was taken. As soon as any part of the material is placed where it is in- 

 tended to remain, they turn round and give it a smart blow with the tail. 

 The same sort of blow is struck by them, upon the surface of the water, 

 when they are in the act of diving. 



" The outside of the hut is covered, or plastered with mud, late in the 

 autumn, and after frost has begun to appear. By freezing, it soon becomes 

 almost as hard as stone, effectually excluding their great enemy, the wolve- 

 rene, during the winter. Their habit of walking over the work frequently 

 during its progress, has led to the absurd idea of their using the tail as a 

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