138 Castokid^. MAMMALIA. Castoriu^. 
it from freezing to the bottom. The heavers that 
build their houses in small rivers and creeks, in which 
water is liable to he drained off when the back supplies 
are dried up by the frost, are wonderfully taught by 
instinct to provide against that evil by making a dam 
quite across the river, at a convenient distance from 
their houses. The heaver dams differ in shape accord- 
ing to the nature of the place in which they are built. 
If the water in the river or creek have hut httle motion, 
the dam is almost straight; but when the current is 
more rapid, it is always made with a considerable 
curve, convex towards the stream. The materials 
made use of are driftwood, green willows, birch, and 
poplars, if they can he got ; also, mud and stones 
intermixed in such a manner as must e^ddently con- 
tribute to the strength of the dam ; hut there is no 
other order or method observed in the dams, except 
that of the work being carried on with a regular sweep, 
and all the parts being made of equal strength. In 
places which have been long frequented by heavers 
undisturbed, their dams by frequent repairing become 
a solid bank, capable of resisting a strong force both of 
water and ice ; and as the willow, poplar, and birch 
generally take root and shoot up, they by degi'ees form 
a regular kind of planted hedge, which I have seen in 
some places so tall that birds have built their nests 
among the branches. The heaver houses are built of 
the same materials as their dams, and are always pro- 
portioned in size to the number of inhabitants, which 
seldom exceeds four old and six or eight young ones ; 
though by chance I have seen above double that nmn- 
ber. Instead of order or regulation being observed in 
rearing their houses, they are of much ruder structure 
than their dams ; for, notwithstanding the sagacity of 
tliese animals, it has never been observed that they 
aim at any other convenience in their houses than to 
have a dry place to lie on ; and there they usually eat 
their victuals, which they occasionally take out of the 
water. It frequently happens that some of the large 
houses are found to have one or more partitions, if they 
deserve that appellation ; hut it is no more than a part 
of the main building, left by the sagacity of the beaver 
to support the roof. On such occasions it is common 
for those different apartments, as some are pleased to 
call them, to have no communication with each other 
but by water ; so that, in fact, they may be called 
double or treble houses, rather than different apart- 
ments of the same house. I have seen a large beaver 
house built in a small island, that had near a dozen 
apartments under one roof ; and, two or three of these 
only excepted, none of them had any communication 
with each other hut by water. As there were beavers 
enough to inhabit each apartment, it is more probable 
that each family knew their own, and always entered 
at their own doors, without any further connection 
with their neighbours than a friendly intercourse, and 
to join their united labours in erecting their separate 
habitations, and building their dams where required. 
Travellers who assert that the heavers have two doors 
to their houses, one on the land side and the other 
next the water, seem to he less acquainted with these 
animals than those who assign to them an elegant suite 
of apartments. Such a construction would render 
their houses of no use, either to protect them from 
then- enemies or guard them against the extreme cold 
of winter. So far are the beavers from driving stakes 
into the ground when building their houses, that they 
lay most of the wood crossways and nearly horizontal, 
and without any other order than that of leaving a 
hollow or cavity in the middle. When any unneces- 
sary branches project inward they cut them off with 
their teeth, and throw them in among the rest to 
prevent the mud from falling through the roof. It is a 
mistaken notion that the wood-work is first completed 
and then plastered ; for the whole of their houses, as 
well as their dams, are from the foundation one mass of 
mud and wood mixed with stones, if they can be pro- 
cured. The mud is always taken from the edge of the 
bank, or the bottom of the creek or pond, near the door 
of the house ; and though their fore-paws are small, 
yet it is held so close up between them under their 
throat tliat they carry both mud and stones, while they 
always drag the wood with their teeth. All then- 
work is executed in the night ; and they are so expe- 
ditious that in the com’se of one night I have knoTO 
them to have collected as much mud as amounted to 
some thousands of their little handfuls. It is a gi-eat 
piece of policy in these animals to cover the outside of 
their houses every fall with fresh mud, and as late as 
possible in the autumn, even when the frost becomes 
pretty severe ; as by this means it soon freezes as hard 
as a stone, and prevents their common enemy, the- 
wolverene, from disturbing them during the whiter. 
And as they are frequently seen to walk over them, 
and sometimes to give a flap with their tail, particu- 
larly when plunging mto the water, this has, without 
doubt, given rise to the vulgar opinion that they used 
their tails as a trowel with which they plaster their 
houses ; whereas that flapping of the tail is no more 
than a custom which they always preserve even when 
they become tame and domestic, and more particularly 
so when they are startled. Their food consists of a 
large root, something resembling a cabbage stalk, 
which grows at the bottom of the lakes and rivers 
(the plant being, according to Sir John Kichardson, 
the yellow water lily, Nuphar luteum). They also 
eat the bark of trees, particularly tliose of the poplar, 
birch, and \villow ; but, the ice preventing them from 
getting to the land in the winter, they have not any 
barks to feed on during that season, except that of 
such sticks as they cut down in summer, and throw 
into the water opposite the doors of their houses; 
and as they generally eat a gi-eat deal, the roots above 
mentioned constitute a principal part of their food 
during the winter. In summer they vary their diet by 
eating various kinds of herbage, and such berries as 
grow near their haunts during that season. When the 
ice breaks up in the spring the Beavers always leave 
their houses, and rove about until little before tifie fall 
of the leaf, when they return again to tlieir old habita- 
tions, and lay in their winter stock of wood. They 
seldom begin to repair the houses till the frost com- 
mences, and never flnish the outer coat till tire cold is 
pretty severe, as hath been already mentioned. When 
they erect a new habitation they begin felling the 
wood early in summer, but seldom begin to build until 
