broad horizontal
flattened tail, which is nearly of an oval form, but rises into a slight
convexity on its upper surface, and is covered with scales. His
fore-feet are armed with nails, and serve for the purpose of hands--
indeed, he vies with the monkey in the use he can make of them. The
hind-feet are webbed, and with these--together with his tail, which acts
as a rudder--he is enabled to swim rapidly through the water. The
beaver is a rodent, with a short head and broad blunt snout, and his
incisor teeth are remarkably large and hard, enabling him to bite
through wood with wonderful ease and rapidity. So great is their
hardness, that formerly the Indians were accustomed to use them as
knives for cutting bone and fashioning their horn-tipped spears.

The beaver, it has been said, always chooses banks by the side of a lake
or river of sufficient depth to escape being frozen to the bottom, even
during the hardest frost. Thus, he can at all times obtain a supply of
water, on which his existence depends; indeed, the bark on which he
lives requires to be moistened before it becomes fit for food. When
instinct teaches a colony of beavers that the water is not of sufficient
depth to escape freezing throughout, they provide against the evil by
making such a dam as has been mentioned, across the stream, or the
outlet of the lake, at a convenient distance from their habitations.
The plan of these dams varies according to the character of the lake or
stream. If the current is but slight, they build the dam almost
straight; but where the water runs at a rapid rate, it is almost always
constructed with a considerable curve, the convex side towards the
stream. Frequently, in such cases, if there is any small island in the
centre, it is taken advantage of, and the dam is built out to it from
either bank. They make use of a variety of materials; employing
driftwood when it can be obtained, to save themselves the trouble of
cutting down trees. This they tow to the spot, and sink it horizontally
with mud and stones. They also employ pieces of green willows, birch,
and poplars, intermixing the whole with mud and gravel, in a manner
which contributes greatly to the strength of the dam. They observe,
however, no order or method in the work, placing their materials as they
can obtain them, except that they make the dam maintain its regular
sweep, and form all parts of equal strength. They carry the mud and
stones in their fore