keep out of sight; so there was no longer anything to be gained by concealment. Pacing the crest, he made 26 it to be about one hundred feet in length. At the centre, and through a great part of its length, it was a little over three feet high, its ends diminishing gradually into the natural rise of the shores. The base of the dam, as far as he could judge, seemed to be about twelve feet in thickness, its upper face constructed with a much more gradual slope than the lower. The whole structure, which was built of poles, brush, stones, and earth, appeared to be very substantial, a most sound and enduring piece of workmanship. But along the crest, which was not more than a foot and a half in width, it was built with a certain looseness and elasticity for which he was at a loss to account. Presently he observed, however, that this dam had no place of overflow for letting off the water. The water stood in the pond at a height that brought it within three or four inches of the crest. At this level he saw that it was escaping, without violence, by percolating through the toughly but loosely woven tissue of sticks and twigs. The force of the overflow was thus spread out so thin that its destructive effect on the dam was almost nothing. It went filtering, with little trickling noises, down over and through the whole lower face of the 27 structure, there to gather again into a brook and resume its sparkling journey toward the sea.

The long upper slope of the dam was smoothly and thoroughly faced with clay, so that none of its framework showed through, save here and there the butt of a sapling perhaps three or four inches in diameter, which proclaimed the solidity of the foundations. The lower face, on the other hand, was all an inexplicable interlacing of sticks and poles which seemed at first glance heaped together at haphazard. On examination, however, the Boy found that every piece was woven in so firmly among its fellows that it took some effort to remove it. The more he studied the structure, the more his admiration grew, and his appreciation of the reasoning intelligence of its builders; and he smiled to himself a little controversial smile, as he thought how inadequate what men call instinct would be to such a piece of work as this.

But what impressed him most, as a mark of engineering skill and sound calculation on the part of the pond-people, was the direction in which the dam was laid. At either end, where the water was shoal, and comparatively dead even in time of freshet, the dam ran straight, taking the shortest way. But 28 where it crossed the main channel of the brook, and required the greatest strength, it had a pronounced upward curve to help it resist the thrust of the current. He contemplated this strong curve for some time; then, a glance at the sun reminding him that it was near noon, he took off his cap to the low-domed house in the water and made haste back to camp for dinner.

CHAPTER III
In the Under-water World

MEANWHILE, in the dark chamber and the long, dim corridors of the House in the Water there was great perturbation. The battle with the otter had been a tremendous episode in their industrious, well-ordered lives, and they were wildly excited over it. But much more important to them––to all but the big beaver who was now nursing his triumphant wounds––was the presence of Man in their solitude. Man had hitherto been but a tradition among them, a vague but alarming tradition. And now his appearance, yesterday and to-day, filled them with terror. That vision of the Boy, standing tall and ominous on the dam, and afterwards going forward and backward over it, pulling at it, apparently seeking to destroy it, seemed to portend mysterious disasters. After he was gone, and well gone, almost every beaver in the pond, not only from the main house but also 30 from the lodge over on the bank, swam down and made a flurried inspection of the dam, without showing his head above water, to see if the structure on which they all depended had been tampered with. One by one, each on his own responsibility, they swam down and inspected the water-face; and one by one they swam back, more or less relieved in their minds.

All, of course, except the big beaver who had been in the fight. If it had not been for that vision of the Boy, he would have crept out upon the dry grass of the little island and there licked and comforted his wounds in the comforting sunlight. Now, however, he dared not allow himself that luxury. His strong love of cleanliness made him reluctant to take his bleeding gashes into the house; but there was nothing else to be done. He was the head of the household, however, so there was none to gainsay him. He dived into the mouth of the shorter of the two entrances, mounted the crooked and somewhat steep passage, and curled himself upon the dry grass in one corner of the dark, secluded chamber. His hurts were painful, and ugly, but none of them deadly, and he knew he would soon be all right again. There was none 31 of that foreknowledge of death upon him which sometimes drives a sick animal to abdicate his rights and crawl away by himself for the last great contest.

The room wherein the big beaver lay down to recover himself was not spacious nor particularly well ventilated, but in every other respect it was very admirably adapted to the needs of its occupants. Through the somewhat porous ceiling, a three-foot thickness of turf and sticks, came a little air, but no light. This, however, did not matter to the beavers, whose ears and noses were of more significance to them than their eyes. In floor area the chamber was something like five feet by six and a half, but in height not much more than eighteen inches. The floor of this snug retreat was not five inches above the level of the water in the passages leading in to it; but so excellently was it constructed as to be altogether free from damp. It was daintily clean, moreover; and the beds of dry grass around the edges of the chamber were clean and fresh.

From this room the living, sleeping, and dining room of the beaver family, ran two passageways communicating with the outside world. Both of these were roofed over to a point well outside the 32 walls of the house, and had their opening in the bottom of the pond, where the water was considerably more than three feet in depth. One of these passages was perfectly straight, about two feet in width, and built on a long, gradual slope. It was by this entrance that the house-dwellers were wont to bring in their food supplies, in the shape of sticks of green willow, birch and poplar. When these sticks were stripped clean of their bark, which was the beavers’ chief nourishment, they were then dragged out again, and floated down to be used in the repair of the dam. The other passage, especially adapted to quick exit in case of danger from the way of the roof, was about as spacious as the first, but much shorter and steeper. It was crooked, moreover,––for a reason doubtless adequate to the architects, but obscure to mere human observers. The exits of both passages were always in open water, no matter how fierce the frosts of the winter, how thick the armour of ice over the surface of the pond. In the neighbourhood of the house were springs bubbling up through the bottom, and keeping the temperature of the pond fairly uniform throughout the coldest weather, so that the ice, at worst, never attained a thickness of more than a foot and