Beaver
2 of the 6 encyclopedias on this shelf carry an entry for Beaver. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
an aquatic gnawing animal resembling the muskrat. It is the largest rodent now living. At one time the beaver was common throughout northern Europe and North America as far south as central Mexico. Beaver skins were a sort of currency among the American settlers, and formed a considerable article of export to the mother country. The demand for this fur was so great that large trading companies were formed, with posts extending throughout British America . The American range of the beaver is now restricted to a few scattering colonies in northern New England , the Lake Superior region, and from the Rio Grande Valley northward in Canada to the limit of trees. Under shelter of a law forbidding their being trapped, prior to 1910, beavers are said to have become numerous in certain parts of northern Michigan. A few colonies are still found under protection in Russia and Norway. The beaver became extinct in England about the time of Richard I. The life of the beaver is a peculiar one. When a band of beavers take possession of a stream, their first care is to secure a pond of water by constructing a dam. Saplings and brush are gnawed off near the ground, dragged into the water, and laid in the channel lengthwise, where they are weighted down with earth and stones. This process is continued until the entire channel has been filled. They then make their dam water-tight by covering the upper end with earth, grass, and clay. They convey material between their fore-paws, and pat it into place with their feet. The object of the dam is to form a pond so deep that it will not freeze to the bottom in the coldest weather. If at any time a leak is sprung, the beaver hastens to mend it. A burrow with its entrance under water is dug for some distance into the bank, turning upward under an old stump or other place of concealment, where the mother rears her young. The beaver lives chiefly on the bark of the birch, basswood, maple, and poplar. Beavers seldom show themselves in the daytime. The most of their work is done in the evening and morning twilight. The beaver is about thirty inches in length, reddish brown above, and grayish below. It weighs from thirty to fifty pounds. Its pelt is still in great demand. When the long outer hairs are plucked out, the beaver's fur is of unsurpassed softness and durability, ranking perhaps next to that of the seal. The paws are small; in swimming they are folded under the body; they enable the beaver to handle and carry sticks, limbs of trees, mud and stones; he uses his paws as hands while sitting up or walking on his hind legs. The hind legs are the propelling power in swimming, and the feet are fully webbed to the roots of the claws. The beaver has a bare tail shaped like that of a muskrat. It is about nine inches long and four wide. It serves as a rudder. Good authority states that the tail is used to slap the water by way of giving alarm, but that it is not used as a trowel in building dams. The beaver has teeth much like those of a rat. A complete tooth is about five inches in length, one inch of which projects from the skull. The front part of the tooth is very hard, the back part is softer and wears away more rapidly, leaving a keen cutting edge. The beaver is able to cut down large trees even a foot or two in diameter, the branches of which it gnaws off, and drags to the bottom of its pond beneath the reach of frost. It thus secures a food supply for the winter. Large houses or conical piles of sticks, twigs, grass, and moss are built up from the bottom of the pond to a height of several feet above the water. Passages lead from the bottom of the pond into an upper chamber where the beaver spends much of his time in the winter, and to which he daily conveys a branch or two from his stock of food collected in the autumn. After the bark is gnawed off, the bare sticks are thrown out again, and serve for repairs on the dam when spring comes. As a colony of beavers increases in number, more houses are built. In time the timber may be destroyed for such a distance from the pond that the colony may find it necessary to remove to a more wooded region. See Fur ; Hudson Bay Company
Collier's New Encyclopedia (1921)
the English name of the well known rodent mammal castor fiber, or, more loosely, of any species belonging to the genus castor. The animal so designated has in each jaw two powerful incisor teeth, coated with hard enamel, by means of which it is enabled to cut across the trunks of the trees which it requires for its engineering schemes. The hind feet are webbed, and one of the five toes has a double nail. The tail is flattened horizontally, and covered with scales. Large glandular pouches secrete an odoriferous substance called casto- The castor fiber exists through reum. the temperate and colder parts of this country. BEAVER
What Has Changed in the Last Century
Aiton's Encyclopedia in 1910 could list the American beaver's range as "a few scattering colonies" and noted its pelt was "still in great demand"; Collier's in 1921 lumped all beavers under Castor fiber. Both animals have since come back on a scale the writers would have found hard to credit — protection, trapping bans and deliberate reintroduction have restored North American beavers to millions of animals, and the Eurasian beaver, reduced to a handful of relict colonies of the kind Aiton's mentions in Russia and Norway, now again ranges across much of Europe. Zoologists also now treat the American and Eurasian animals as two separate species, Castor canadensis and Castor fiber, which differ in chromosome number and do not interbreed. Most striking of all, the beaver Aiton's says vanished from England around the reign of Richard I has been brought back: animals are living wild in Scottish and English rivers again, and the beaver is valued less as fur than as a "keystone species" whose dams create wetland and slow floodwater.
Written for this edition, 2026.