96 BRITISH . in narrow openings, left at about twenty yards from each other, in a brushwood fence. The noose is attached to a pole, or to a young pliant tree, that springs up on being sprung ; and along the line of fence, on a winter's morning, several are found hung up and strangled. The beaver (castor), whose fur is so valuable, is an animal of astonishing industry, and prudent foresight. In order to secure lodgings and provisions during winter, they live in a state of society, which resembles the civil compact of man, rather than the mere instinctive gregarious habits of other animals. As they must live near water, and frequently in it, they build dams across running brooks, to create an arti¬ ficial lake; and in order to accomplish so great an object, they are obliged to labour in concert. The ingenuity with which they construct their dams, and build apartments or lodgings, is truly astonishing. If the water of the river or creek have little motion, they build their dams straight across ; but if the current be rapid, they make them with a considerable and regular curve against the stream. All the parts are of equal strength and consistency, and constructed of drift wood, green willows, birch, poplars, mud, and stones. These dams, by constant repairing, often become a solid bank, on which trees soon grow. The beavers sometimes build their houses on lakes, and other standing waters, without dams ; but the advan¬ tage of a current, to carry down wood and other necessaries to their habitations, seems to counter¬ balance the laboxir of building a dam.