ITS DAM AND LODGE. 175 



in thickness at the bottom, although they are only two feet or so wide 

 at the summit. 



In forming the dam, the Beaver does not thrust the ends of the stakes 

 into the bed of the river, as is often supposed, but lays them down hor- 

 izontally, and keeps them in their place by heaping stones and mud 

 upon them. The logs of which the dam is composed are about three feet 

 in length, and vary extremely in thickness. Generally, they are about 

 six or seven inches in diameter, but they have been known to measure 

 no less than eighteen inches. An almost incredible number of these 

 logs is required for the completion of one dam, as may be supposed 

 from the fact that a single dam will sometimes be three hundred yards 

 in length, ten or twelve feet thick at the bottom, and of a height vary- 

 ing according to the depth of water. 



Before employing the logs in this structure, the Beavers take care to 

 separate the bark, which they carry away, and lay up for a winter store 

 of food. 



Near the dams are built the beaver-houses, or " lodges," as they are 

 termed — edifices as remarkable in their way as that which has just 

 been mentioned. They are composed chiefly of branches, moss, and 

 mud, and will accommodate five or six Beavers together. The form 

 of an ordinary-sized Beaver's lodge is circular, and its cavity is about 

 seven feet in diameter by three feet in height. The walls of this struc- 

 ture are extremely thick, so that the external measurement of the same 

 lodges will be fifteen or twenty feet in diameter, and seven or eight feet 

 in height. The roofs are all finished ofi* with a thick layer of mud, 

 laid on with marvellous smoothness, and carefully renewed every year. 

 As this compost of mud, moss, and branches is congealed into a solid 

 mass by the severe frosts of a North American winter, it forms a very 

 sufficient defence against the attacks of the Beaver's great enenj^, the 

 wolverene, and cannot readily be broken through, even with the help 

 of iron tools. The precise manner in which the Beavers perform their 

 various tasks is not easy to discern, as the animals work only in the 

 dark. 



Around the lodges the Beavers excavate a rather large ditch, too 

 deep to be entirely frozen, and into this ditch the various lodges open, 

 so that the inhabitants can pass in or out without hindrance. This 

 precaution is the more necessary, as they are poor pedestrians, and 

 never travel by land as long as they can swim by water. Each lodge 

 is inhabited by a small number of Beavers, whose beds are arranged 

 against the wall, each bed being separate, and the centre of the cham- 

 ber being left unoccupied. 



In order to secure a store of winter food, the Beavers take a vast 

 number of small logs, and carefully fasten them under water in the 

 close vicinity of their lodges. When a Beaver feels hungry he dives 



