the best provender. The overstocking of
districts is the chief cause of beaver migration.
Students of mountain ranges, water-sheds,
and river systems, will not find it difficult
to understand how migratory beavers ascending
rivers, brooks, and rills, and living in bank
and swamps, have spread themselves far and
wide.

An emigrant who can swim far, dive a long
time, and cut wood with self-sharpening chisels,
the beaver is still further endowed for his
career, by his talents as an engineer. As he can
travel best in the water, and as his food floats
in water, he uses his engineering skill in
constructing ponds, dams, and canals, for the
transport of his wood cuttings. His natural home
is a burrow, but when he cannot make a burrow
he builds lodges and porches. His forepaws or
hands are not particularly handy for engineering
and building labours; but the brain he has
inherited makes up for all deficiencies. The
brain of the beaver is smooth; and the size
proportionally to the body one to five hundred and
thirty- two. The absence of convolutions
bespeaks an animal which does not lie in wait
for other animals; yet beavers can adapt
themselves to circumstances as they arise, in
an ingenious way. When the progress of
cultivation expels them from their burrows
in the banks of rivers, and drives them up
unexplored brooks, and into sequestered swamps,
they vary their ways of obtaining their food
and shelter, according to varying
circumstances.

For the purpose of realising this aspect of
beaver life, we must accompany Mr. Morgan
to the beaver district, which lie studied for
years, on the level summit of the range of hills
skirting the southern shore of Lake
Superior, immediately west of Marquette. It is
eight miles long from east to west, by six
broad from north to south. Many small lakes
lie, and many rivulets run, in this district,
which the beavers, until recently, possessed as
immemorially their own. Leaving out dams
less than fifty feet long, there are in this
beaver district sixty-three dams, some of them
five hundred feet long, and forming ponds covering
from a quarter of an acre to twenty or sixty
acres of ground. This district is overspread with
a thick forest, and is a wilderness to be
traversed by none but experienced woodmen on
Indian trails. Near the streams grow tamarack
and spruce trees: on the rising ground, birch,
white and yellow; maple, soft and bird's-eye;
poplar, and ash: upon the hills, pines, oak,
and sugar maple; whilst among the bushes
occur the willow, alder, and cranberry. Now,
the question of the engineering beavers is, how
they may, from the banks of the streams, reach
the succulent twigs and branches of these trees
and bushes, by water?

The beavers in Europe and America, living in
burrows on river hanks, do not construct dams,
although they build sometimes what are called
false lodges— a sort of porches which mask the
entrances to their burrows. Dams are built to
make ponds for transport by water of wood
cuttings. They make the tamarack and spruce
trees accessible by water. When their burrows
or lodges are assailed, the beavers take refuge
in their ponds. The level of the pond is
generally about two feet above the entrance to the
lodge or burrow. This level must be maintained,
if the beavers are to fee! safe; and they
control it by their dams. The first impression
on observers of these dams, was, that they were
the work of communities, like the nests of wasps
or hives of bees. But this view is not
supported by the results of closer observation.
Mr. Morgan is convinced fhat the larger dams
were not built by many beavers working
together, but grew from small beginnings, year
after year, until the ponds became as large, in
the course of centuries, as the localities would
permit them to be made. A single family
began, and made a dam; as trees were cut
down, the necessity for enlarging the pond
increased; the accommodation for families
was extended; and ponds, covering,
perhaps, sixty acres of ground, were formed,
large enough to have been called lakes in
Europe.

And this is the way in which human towns
grow. Home was not built in a day, or by
a colony or community. But we submit that
a beaver pond, like a human town, is kept
up by the attention, care, oversight, vigilance,
and labour, of a community. Just as, along
the coast of Sussex, the owners of land
and occupiers of houses at certain points,
fearful of sharing the fate of the churches,
monasteries, and towns, which have been washed
away by the sea, have combined under the
compulsion of a common interest to maintain their
sea wall, the beavers combine to keep up their
dams. This is Mr. Morgan's own showing.
Judging from the extent of the meadows, the
hummocks formed by decayed vegetation, and
the masses of solid materials in the dams, he
says they must have existed for hundreds and
thousands of years; and must have been kept
up by continuous repairs.

There are two kinds of dams; the wood dam,
and the earth dam; so called according as poles
or mud predominate in the structure. The
wood dam is formed of interlaced sticks and
poles; and the water finds its way through
it. The earth dam, though held together with
wood, is composed chiefly of earth, which hides
the sticks and becomes a solid dike, sloping on
both sides. The surplus water cannot get
through this dike; and therefore a single opening
is made for it, a sluice: which is the object
of the attention and solicitude of the
community.

The dam is preferably built on a hard and
stony foundation. Stakes are not driven into
the ground. Small sticks and brush cemented
with mud and kept down by stones, form an
embankment. On a stream issuing from Lake
Diamond, a stick dam is to be seen two
hundred and sixty feet ten inches long, and six feet
two inches high. The streamlet it crosses is