-paws; and in one night will collect as much as
amounts to many thousands of their little loads. When driftwood is not
to be found, they obtain the timber they require from the groves
skirting the lake or pond. To do this, they squat on their hams, and
rapidly gnaw through the stems of trees from six to twelve or fourteen
inches in diameter, with their powerful incisors. Sometimes a tree will
not fall prostrate, the boughs being caught by its neighbours. But the
beaver is not to be disappointed; he sets to work and gnaws away a
little above the first place, thus giving it a fresh start, in order
that the impetus may disengage it from the branches which keep it up.
The tree being cut up, the beavers, uniting, tow the pieces down to the
dam. They then plunge into the water and bring up the mud and small
stones with which to keep it sunk. A long constructed dam, by being
frequently repaired with fresh mud, becomes at length a solid bank,
capable of resisting a heavy rush, either of water or ice; and as the
willow, poplar, and birch generally take root and shoot up, they by
degrees form a regularly planted hedge, which in some places becomes so
tall that birds have been known to build their nests among the branches.
These beaver dams also form bridges, over which two or three men may
pass abreast, and lead their horses, without risk of breaking through.
So rapidly do the members of the industrious community labour, that even
the most serious damage to their dams, or habitations, is quickly
repaired. They always carry the mud and stones in their fore-paws,
pressed against their chins, but they drag the wood with their teeth.

The creature does not employ its broad tail, as was once supposed, to
plaster down its mud-work, nor does it use it as a vehicle for
transporting materials; its sole object being to guide it when in the
water, and as a counterpoise, by moving it in an upward direction, to
the tendency it would otherwise have of sinking head-foremost. The
creatures cover the outside of their houses every autumn with fresh mud
as soon as the frost becomes severe. By this means it freezes as hard
as stone, and prevents their common enemy, the wolverene, disturbing
them during the winter. From the beaver being seen to flap its tail
when moving over its work, but especially when about to plunge into the
water, has arisen the idea that it uses this member as a trowel. This
custom it preserves even when it becomes ta