110 NATURAL HISTORY. 



give with that member when they dive. In order that their 

 pond may not be too deep, they always leave an opening in 

 the dam to let the water escape when it rises above a certain 

 height. 



They cut most of their wood in the summer, taking care to 

 choose trees above their houses, so that the stream floats them 

 down to the place where they wish to use them. They also 

 lay up stores of food for the winter, by cutting a number of 

 green branches and sinking them near the door of their habita- 

 tions, where they are held firm by stones laid on the summit 

 of the heap. 



During the severe winter, their mud-built houses freeze quite 

 hard, and prevent the wolverine, their greatest enemy except 

 man, from breaking through and devouring the inmates. 



The fur of the Beaver is exceedingly valuable, especially for 

 the manufacture of hats, and is greatly sought after. The 

 hunting season is in winter, when the beavers are quietly in 

 their houses. The hunters, armed with spears, &c. break the 

 tops of the houses. The alarmed beavers instantly rush out 

 and pass under the ice to certain hiding-places in the bank. 

 The hunter then discovers the position of the hole in the bank 

 by the sound of his spear struck against the ice ; he then 

 breaks a hole and spears the animal in its place of fancied se- 

 curity. A substance called Castor was formerly obtained 

 from the Beaver and much used in medicine, but is now dis- 

 carded. 



When in captivity the Beaver soon becomes tame, and 

 will industriously build dams across the corner of a room 

 with brushes, boots, fire-irons, books, or any thing it can find. 

 When its edifice is finished it sits in the centre apparently sat- 

 isfied that it has made a beautiful structure to dam up the 

 river a proof that the ingenuity of the Beaver is not caused 

 by reason but by instinct. 



The fur of the Beaver, like that of many other animals, con- 

 sists of a fine wool intermixed with long and stiff hairs. The 

 hairs are useless, but the peculiar construction of the fur causes 

 it to penetrate and fix itself into the felt which forms the body 

 of a hat. The length of the Beaver is about three feet and a 

 half. 



Several genera are omitted. 



