t unique feature of the animal's body
is the famous mud-plastering tail, which is oft-times a foot long, five
inches in width, and an inch in thickness. The colour of the beaver
varies; there are black beavers, white beavers, and brown beavers. The
black are the best known.

The beaver is well equipped for defending himself, and for carrying out
his architectural schemes. His jet black tail, which is like a large
paddle, covered with horny scales, he uses in many ways. With it he
turns the body in any desired direction while swimming and diving, and,
in time of danger, employs it as a sound board, or paddle. When alarmed
at night, he dives into the water, and, by means of his tail, splashes
so violently as to give warning to all beavers within a half-mile
distance. The stroke of the tail sounds not unlike a pistol shot. As
soon as a beaver sounds the alarm all others dive underneath the water.
His teeth are expressly suited by nature for cutting and chiselling out
trees.

The dam is the beaver's masterpiece. In the alder or birch swamps, where
he usually lives, he oft-times builds from six to eight little dams from
knoll to knoll, and in this way makes a pond sufficiently large for his
purposes. The average beaver dam is from twenty to thirty feet long; but
they differ greatly in size. There is one on a branch of Arnold's River
in Canada, where the stream is twenty-one feet wide and two feet deep,
which is especially well built. The dam is seven feet high, and rises
five to six feet above the pool. It is constructed mainly of alder
poles, which are arranged side by side, and their length is parallel
with the direction of the current. To create a pond for himself and
provide against drought is the chief aim of the beaver in building his
dam.

Just how these dams are built; who plans the job; who sees that it is
carried out; whether each works under his own impulse or whether they
co-operate; when they begin and how they finish; all these things are
unknown to man. The investigation of such questions is almost
impossible. It is generally believed, however, that beavers work in
gangs under a common "boss" or "overseer," and it is a known fact that
they work only at night. During a dark, rainy night they accomplish
twice as much as on a moonlight night. No doubt the darkness gives them
a sense of security which aids their work. Anyway, in the completed job,
we see the evidences of a skilled engineer and architect, and on