d poplars if they can be got; also mud and stones, intermixed in such
a manner as must evidently contribute to the strength of the dam; but
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
beavers undisturbed, their dams, by frequent repairing, become a solid
bank, capable of resisting a great force both of water and ice; and as
the willow, poplar, and birch generally take root and shoot up, they by
degrees form a regular planted hedge, which I have seen in some places
so tall, that birds have built their nests among the branches.

"The beaver-houses are built of the same materials as their dams, and
are always proportioned in size to the number of inhabitants, which
seldom exceeds four old and six to eight young ones; though, by chance,
I have seen above double the number. Instead of order or regulation
being observed in rearing their houses, they are of a much ruder
structure than their dams; for, notwithstanding the sagacity of these
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),
but 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
these 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 apartments 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 but by water. As there were beavers enough to inhabit each
apartment, it is more than probable that each family knew their own, and
always entered at their own door, 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 beavers have two doors
to their h