NORTHERN OCEAN. 229 
vers or crecks, in which the water is liable tobe 1771. 
drained off when the back fupplies are dried up a haat 
by the froft, are wonderfully taught by infliné 
to provide againft that evil, by making a dam 
quite acrofs the river, at a convenient diftance 
from their houfes. ‘This I look upon as the mott 
curious piece of workmanfhip that is performed 
by the beaver; not fo much for the neatnefs of 
the work, as for its ftrength and real fervice; 
and at the fame time it difcovers fuch a degree 
of fagacity and forefight in the animal, of ap- 
proaching evils, as is little inferior to that of 
the human fpecies, and is certainly peculiar to 
thofe animals. 
‘The beaver-dams differ in fhape according to 
the nature of the place in which they are built. 
If the water inthe river or creek have but little 
motion, the dam is almoft ftraight; but when 
the current is more rapid, it is always made with 
a confiderable curve, convex toward the ftream. 
The materials made ufe of in thofe dams are 
drift-wood, green willows, birch, and poplars, if 
they can be got; alfo mud and ftones, intermixed 
in fuch a manner as mutt evidently contribute to 
the ftrength of the dam; but in thefe dams 
there is no other order or method obferved, ex- 
cept that of the work being carried on with a 
regular fweep, and all the parts being made of 
equal {trength. 
In places which have been long frequented by 
beaver undifturbed, their dams, by frequent re- 
Q2 pairing, 
