464 THE BEAVER. 



formation of works which may fairly be considered as belonging to the profession of the 

 engineer. They prefer to make their habitations by small clear rivers and creeks, or close to 

 large springs, although they sometimes take up their abode on the banks of lakes. 



Lest they should not have a sufficient depth of water in all weathers and at all seasons, 

 the Beavers are in the habit of building veritable dams, for the purpose of raising the water to 

 the required level. These dams are composed of tree-branches, mud, and stones, and in order 

 effectually to resist the action of the water, are about ten or twelve feet in thickness at the 

 bottom, although they are only two feet or so wide at the summit. When the different parts 

 of the stream run with varying velocity, the formation of the dam is really a triumph of 

 engineering skill, for wherever the stream is gentle, the dam is built straight across it ; but 

 wherever the current runs smartly, the dam is curved so as to present a convex surface to its 

 force. It often happens that when a dam has been made for some years, its dimensions 

 become very large, in consequence of the trees and branches that are intercepted by it, and in 

 process of time it sprouts thickly with vegetation, and even nurtures trees of some dimensions. 



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 horizontally, 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 in diameter. 

 An almost incredible number of these logs are 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 varying 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 chiefly composed 

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

 an ordinarily sized Beaver's lodge is circular, and its cavity is about seven feet in diameter by 

 three feet in height. The walls of this structure 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 off with a thick layer of mud, laid on with marvel- 

 lous 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 Beavers' great enemy, 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 chamber 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 to the store heap, drags out a suitable log, carries it to a sheltered and 

 dry spot, nibbles the bark away, and then either permits the stripped log to float down the 

 stream, or applies it to the dam. 



Their teeth are wonderfully powerful and sharp, and their jaws are possessed of singular 

 strength. 



So sharp are their teeth, and with such address does the animal use them, that a tame 

 Beaver has repeatedly been seen to take a potato or an apple in his fore-paws, to sit up on his 

 hind feet, and by merely pressing the apple against his lower incisors, and manipulating it 



