OF NATURAL HISTORY; 31s 



thinnefl: part of the bank, the beavers make two or three floping 

 holes, to allow the furface-water to efcape. Thefe they enlarge or 

 contrail in proportion as the river rifes or falls ; and, when any 

 breaches are made in the bank by fudden or violent inundations, 

 they know bow to repair them when the water fubfides. 



Hitherto all thefe operations were performed by the united force 

 and dexterity of the whole community. They now feparate into 

 fmaller focieties, who build cabins or houfes. Thefe cabins are con- 

 ftrudted upon piles near the margin of the river or pond, and have 

 two openings, one for the animals going to the land, and the other for 

 throwing themfelves into the water. The form of thefe edifices is 

 either round or oval, and they vary in fize from four or five to eight 

 or ten feet in diameter. Some of them confift of three or four ftories. 

 Their walls are about two feet thick; and are raifed perpendicularly 

 upon planks, or plain flakes, which ferve both for foundations and 

 floors to their houfes. When they confift of but one ftory, they rife 

 perpendicularly a few feet only, afterwards aflume a curved form, and 

 terminate inadome or vault, which anfwers the purpofe of aroof. They 

 are built with amazing folidity, and neatly plaftered with a kind of ftuc- 

 co both within and without. In the application of this mortar the tails 

 of the beavers ferve for trowels, and their feet for plafliing. Their 

 houfes are impenetrable to rain, and refift the moft impetuous winds. 

 In their conftrudion, they employ different materials, as wood, ftone, 

 and a kind of fandy earth, which is not liable to be diiTolved in wa- 

 ter. The wood they ufe is generally of the light and tender kinds, as 

 alders, poplars, and willows, which commonly grow on the banks 

 of rivers, and are more eafily barked, cut, and tranfported, than the 

 heavier and more folid fpecies of timber. They always begin the 

 operation of cutting trees at a foot or a foot and a half above the 

 ground : They labour in a fitting pofture ; and, befide the conve- 

 nience of this pofture, they enjoy the pleafure of gnawing perpe- 

 2 R r 2 tually 



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