This animal was known to the ancients for its possession of that sebaceous matter called castor, secreted by two large glands near its genitals and anus, and of which each animal has about two ounces; but they appear to have been unacquainted with its habits and economy, with that mental contrivance and practical dexterity, which in its natural state so strikingly distinguish it. Beavers are found in the most northern latitudes of Europe and Asia, but are most abundant in North America.

In the months of June and July, they assemble in large companies to the number of two hundred, on the banks of some water, and proceed to the formation of their establish ment. If the water be subject to risings and fallings, they erect a dam, to preserve it at a constant level; where this level is naturally preserved, this labour is superseded. The length of this dam is occasionally eight feet. In the preparation of it, they begin with felling some very high, but not extremely thick tree, on the border of a river, which can be made to fall into the water; and, in a short time, this is cr fected by the united operation of many, with their fore-teeth, the branches being afterwards cleared by the same process A multitude of smaller trees are found necessary to complete the fabric, and many of these are dragged from some distance by land, and formed into stakes ; the fixing of which is a work of extreme difficulty and perseverance, some of the bea-vers with their teeth raising their large ends agiinst the cross-beam, while others at the bottom dig with their fore-feet the holes in which the points are to be sunk. A series of these stakes, in several rows, is established from one bank of the river to the other, in connection with the cross-tree, and the intervals between them are filled up by vast quantities of earth, brought from a distance, and plashed with materials adapted to give it tenacity, and prevent its being carried off. The bark is formed at the bottom, of about the; width of twelve feet, diminishing as it approaches the surface of the water, to two or three; being thus judiciously constructed to resist its weight and efforts by the inclined plane instead of perpendicular opposition.

These preparations, of such immense magnitude and toil, being completed, they proceed to the construction of their mansions, which are raised on piles near the margin of the stream or lake, and have one opening from the land, and another by which they have instant access to the water. These buildings are usually of an orbicular form, in general about the diameter of ten feet, and comprehending frequently several stories. The foundation walls are nearly two feet in thickness, resting upon planks or stakes, which constitute also their floors. In the houses of one story only, the walls, which in all cases are plastered with extreme neatness both externally and within, after rising about two feet perpendicularly, approach each other, so as at length to constitute, in closing, a species of dome. In the application of the mortar to their habitations, the tails as well as feet of the beavers are of essential service. Stone, wood, and a sandy kind of earth, are employed in their structures, which, by their compactness and strength, completely preclude injury from winds and rain. The alder, poplar, and willow, are the principal trees which they employ ; and they always begin their operations on the trunk, at nearly two feet above the ground; nor do they ever desist from the process till its fall is completed. They sit instead of stand, at this labour, and while reducing the tree to the ground, derive a pleasure at once from the success of their toils, and from the gratification of their palate and appetite by the bark, which is a favourite species of food to them, as well as the young and tender parts of the wood tself.

For their support in winter, ample stores are laid up near each separate cabin; and occasionally, to give variety and luxury to their repasts during a long season, in which their stores must have become dry and nearly tasteless, they will make excursions into the neighbouring woods for fresh supplies. Depredations by the tenants of one cabin on the magazines of another are unknown, and the strictest notions of property and honesty are universal. Some of their habitations will contain six only, others twelve, and some even twenty or thirty inhabitants ; and the whole village or township contains in general about twelve or fourteen habitations. Strangers are not permitted to intrude on the vicinity ; but, amidst the different members of the society itself, there appears to prevail that attachment and that friendship which are the natural result of mutual co-operation, and of active and successful struggles against difficulty. The approach of danger is announced by the violent striking of their tails against the surface of the water, which extends the alarm to a great distance ; and, while some throw themselves for security into the water, others retire within the precincts of their cabins, where they are safe from every enemy but man.

The neatness as well as the security of their dwellings is remarkable, the floors being strewed over with box and fir, and displaying the most admirable cleanness and order. Their general position is that of sitting, the upper part of the body, with the head, being considerably raised, while the lower touches, and is somewhat indeed immersed in, the water. This element is not only indispensable to them in the same way as to other quadrupeds, but they carefully preserve access to it even when the ice is of very considerable depth, for the purpose of regaling themselves by excursions to a great extent under the frozen surface. The most general method of taking them is by attacking their cabins during these rambles, and watching their approach to a hole dug in the ice at a small distance, to which they are obliged, after a certain time, to resort for respiration.

If a man, who had never been informed of the industry of beavers and their manner of building, were shown the edifices that they construct, he would suppose them to be the work of most eminent architects. Every thing is wonderful in the labours of these amphibious animals ; the regular plan, the size, the solidity, and the admirable art of these buildings, must fill every attentive observer with astonishment.

The works of beavers have a great resemblance to those of men ; and upon their first appearance we may imagine them to be produced by rational and thinking beings ; but when we examine them nearer, we shall find that in all their proceedings, these animals do not act upon the principles of reason, but by an instinct which is implanted in them by nature. If reason guided their labours, we should naturally conclude that the buildings which they now construct would be very different from those they formerly made, and that they would gradually advance towards perfection. But we find that they never vary in the least from the rules of their forefathers, never deviate from the circle prescribed to them by nature, and the beavers of to-day build exactly after the same plan as those which lived before the deluge. But they are not the less worthy of our admiration. In these sagacious creatures we have an example of the great diversity there is in the instinct of animals - how superior is the instinct of the beaver to that of the sheep!

The flesh of the anterior part of the bodies of beavers re sembles that of land animals in substance and flavour ; while that of the lower possesses the taste, and smell, and lightness of fish.

The sexual union among these animals is connected with considerable individual choice, sentiment, and constancy.- Every couple pass together the autumn and winter, with the most perfect comfort and affection. About the close of winter, the females, after a gestation of four months, produce, in general, each two or three young, and soon after this period they are quitted by the males, who ramble into the country to enjoy the return of spring; occasionally returning to their cabins, but no longer dwelling in them. When the females have reared their young, which happens in the course of a few weeks, to a state in which they can follow their dams, these also quit their winter residence, and resort to the woods, to enjoy the opening bloom and renovated supplies of nature. If their habitations on the water should be impaired by floods, or winds, or enemies, the beavers assemble with great rapidity to repair the damage. If no alarm of this nature occurs, the summer is principally spent by them in the woods, and on the advance of autumn they assemble in the scene of their former labours and friendships, and prepare with assiduity for the confinement and rigours of approaching winter.

When taken young, the beaver may be tamed without difficulty ; but it exhibits few or no indications of superior intelligence. Some beavers are averse to that association which so strikingly characterizes these animals in general, and satisfy themselves with digging holes in the banks of rivers, instead of erecting elaborate habitations. The fur of these is comparatively of little value.