An idea prevails which ought to be exploded. It is boldly asserted that the beaver builds his dam for the purpose of having a nice swimming pond in the neighborhood of his residence, which is always located in the river's bank. This is not true; for, in every stream which he inhabits, if this was his sole object, he could select many natural places where the water is without a ripple and where it is both deep and broad. The animal has a wiser object in view; and, it consists in providing against the pinching wants of hunger during winter, when nearly everything green has lost its sap and nutrition, and is, as a body, without blood and animation. He therefore chooses a place favorable for obtaining food, and also where his labors will be assisted by natural formations or accidents in the river's course and construction. Having pitched upon the right section to build, he sets to work with his fellows and falls giant trees. In this he again exhibits his wonderful instinct; for, while one party is cutting with their sharp teeth the hard wood of one side of the tree, another division is actively employed on the other side, never forgetting to make, like unto the woodman, the lowest incision on the side the tree is to fall, which, to suit their purposes, is always directly into and across the stream. When a tree is thus fallen, it is attacked in its branches, which are so turned and woven together in the outline of the dam as to catch in their meshes any floating material, or receive the tail-loads of soil and rubbish which they carry to it. Another and another tree are then systematically fallen and arranged as is the first, until the work is finished as completely as if it had been planned and executed by a reasoning mind. The finishing stroke is the transporting of the mud and laying it. In this labor, they show themselves to be excellent masons. They now act in concert. A large gang marches in a line to the bank where they load each other's tails and swim with their cargoes elevated above and free from the water. When they arrive at an unfinished point of the dam they dump the mud and mould it in place. Their houses they have previously built in the river banks. These consist of holes which lead into large and airy subterranean rooms, and which are above the water-mark. In these houses they are said to sleep and live in pairs; and, if we could believe the story of the trapper related many pages back, they imitate human beings in managing their household and in keeping house. The main object they have in staying the progress of the current of the river is to afford a deep place where, having fallen numbers of trees, the deep water will preserve tender and fresh the limbs and shrubs on which to subsist during, not only time present, but also time to come. It is well known that fresh branches of trees and young willows, when placed in water, will keep up partial life for a considerable length of time.