Besides the first, or great dam, the beaver sometimes makes a smaller one lower down the stream. This smaller dam is perhaps a more interesting structure even than the principal one, from the point of view of the beaver’s intelligence. The pond which is formed above it by the now diminished stream, is too small to be of much use to the animal, but by increasing the height of the water behind the great dam, it diminishes the pressure of the stream against it, on the other side, so that there is less fear of the dams bursting. This, too, is by a principle which I should find it difficult to formulate myself—and it can hardly be supposed that the beaver knows anything about it. The surprising thing is that, somehow, practically, he has found it out—that is to say, he knows how to apply it, without having any idea of what he is doing. In carrying the mud and sticks to the water, the beaver walks, it would seem, upon his hind legs, and in placing and working them together, he generally also assumes the upright attitude. The massive tail, by acting as a base or fulcrum, on which the animal can lean back, enables it to do this with the greatest ease. The toes of the forefeet are not webbed, as are those of the hind ones, nor do they aid in swimming, being then pressed against the body, but are used more as hands, at least for the purposes of architecture. With them the beaver scoops up the mud, and holding it between them or pressed against his throat, walks upright to his dam like a little mannikin in a brown fur coat. It used to be thought that the broad, naked tail served the beaver as a trowel, for the laying and plastering of the mud. This was not so entirely an error as one generally reads it is, since Mr. Morgan tells us that “he uses his tail to pack and compress mud and earth, while constructing a lodge or dam, which he effects by heavy and repeated down-strokes,” and he adds, truly enough, “that it performs, in this respect, a most important office, and one not unlike some of the uses of the trowel.” This shows that there was really something in the old idea, but it was imagined also that the beaver, besides using his tail as a trowel, actually prepared mortar with it, from mud. This was a fable, but there was much more truth in the general statement, of which this was only an item, than in the learned _ex cathedrâ_ denial, which denied everything—and so it very often is. As we have seen, both wood and mud enter into the construction of the beaver’s dam, besides stones, which do not play so important a part. I have called the wood “sticks” because that is the word usually employed in America, where beaver-dams are often called “stick-dams.” But these sticks may be of a considerable size, so that we should often rather call them logs, or, at any rate, branches. Branches, gnawed into various lengths, is what they really are, and to obtain them the beaver, which is a rodent, and