It will be remembered that before beginning work on the dam the beavers went to a point a few rods above where it was to be placed and dug three holes running back from the stream. These holes started at different points in the bank but all converged at the top of the knoll.

The water had now set back and covered the lower end of the holes near the stream, but the opening at the top of the knoll was high and dry.

The beavers now set to work with mud, sticks, stones, fine brush, and weeds, and built a circular wall about eight feet in diameter around the hole at the top of the knoll. The wall was about two feet thick and during the first two or three days of building looked for all the world like the snow fort that children build by rolling huge snowballs into a circular wall, and then plastering in the cracks with loose snow, only the beavers' work was more regular and symmetrical than that of the children.

It was now the first of November and freezing a little each night; just the best time imaginable for a beaver to work upon his house, for it was really a house that the beavers were building.

While the November sky was bright with stars, and the milky way was luminous; while the frost scaled over the edges of their little pond, and the fresh north winds rapidly stripped the forest of its last leaves, the beavers worked upon their house with that industry which is proverbial of them.

They brought mud in their paws or on their broad flat tails, and sticks and brush in their teeth and plastered away like skilful masons. When a pile of mud had been placed in the proper position, it would be smoothed off carefully with the patient fore paws or perhaps that broad strong tail would come down upon it with a resounding slap and the trick was done.

When the wall began to round over for the roof, the difficulty began. Here they had to put in rafters. These were formed of pliable sticks of alder or willow, one end being stuck in the mud wall, and the other bent over at the top, until all came together where the chimney would be just like the poles in an Indian's wigwam. Here they also had to use great care in placing the mud, for it would frequently fall through between the rafters, or slide down upon them. If they could work, when it was freezing, the cold froze the mud to the rafters and helped to keep it in place. Several times, part of the roof fell in and had to be relaid, but they still worked away and, finally, all but a very small opening, two or three inches in diameter, had been closed. This opening was the vent or chimney, where foul air might escape. This hole had to be just large enough to permit the escape of hot air, but not large enough to admit any of their enemies.

The same night that the final touches were put upon the roof of this curious dome-shaped house, the ground froze hard, and in the morning the wall of Mr. and Mrs. Beaver's new abode was quite substantial. But later on when the hard freeze had made the earth like rock, this little mud house would be a veritable fortress, capable of withstanding almost any onset with ordinary weapons. Even a man with a crowbar and axe would have found it a hard task to enter this stronghold of these queer little people.

So you see the beaver had planned his work well and the frost and the wind had helped him. He had harnessed the stream to do his work, and made its water protect him from his enemies. Just as men built their castles in days of old, the beaver had made his dam, so that a moat should surround his house, where the drawbridge should always be up, and the only way of entrance or exit should be by water.

You may wonder how after the roof of their house had been closed up, and no door left, the beavers went to and from their dwelling, but do you not remember the three holes that had been dug several weeks before. These were now their three submerged channels to the outer world, through which only a good swimmer could pass. This was the way they went. A plunge down the hole at the centre of the lodge, and a dark form would shoot out at the bank of the river. Perhaps a beaver's head, dripping with water would be poked up, only a few feet from the mud house, or maybe they would go the entire width of the pond before coming to the surface, for they are great swimmers, and can stay down for several minutes without coming to the surface to breathe.

Besides having three doors through which to escape to their water world, the beavers took other precautions against being entrapped in their snug house, or caught in the pond without a place of refuge to flee to.

They searched the bank for places where it was steep or shelving, overhanging the water. At such points they dug burrows back into the bank, gradually running them upward, but stopping a foot or two short of the surface. Here they would scoop out a snug burrow or nest to which they could retreat when living in the house became dangerous. They made three or four such burrows, the lower end of each being under water, and the nest end high and dry, but still underground. By this time they felt that their pond was fairly well fortified, and they set to work, laying in their winter store of food, for they knew that the pond would soon freeze over thus making them prisoners under the ice for the entire winter, so they must make their plans accordingly.

They went to the upper end of the pond and began felling birch, poplar and maple saplings, three or four inches in diameter. These small trees they limbed out, and cut up into pieces about three feet in length, just as a wood-chopper would cut cord wood.

When a tree had been cut up into these convenient pieces, one of the beavers would load it upon the shoulders of the other, who would cling to the stick with his teeth, and they would begin dragging it to the water. The beaver usually went obliquely, dragging the stick after him, with one end trailing. When it had been rolled into the water, it was left to the current which they knew would float it down to the dam. If the channel became blocked and logs lodged along the shore, they pushed them off like the good log-men they were.

It took two or three weeks to cut the winter's supply of wood, which was not for fuel but food. All the logs had been floated down to the dam and secured under water near the lodge, when the great freeze came. It was quite difficult to make the sticks stay under water, but this they managed to do in several ways. Some of them they thrust into the mud, while others were secured under roots, and a large pile was made safe at the dam by thrusting one stick under another and allowing the top sticks to keep the under ones down.

One clear, crisp night, about the first of December, the North Wind awoke and came galloping over the frozen fields, bringing with him legions of frost folks. The fingers of these myriad little people were like icicles, and everything that they touched was congealed. They found the beavers' pond, and danced a merry dance over the sparkling water, and every time that they stooped to touch the clear water, crystals of ice formed and spread in every direction.

It had been a very pleasant autumn, but the North Wind was angry to-night, and he howled like a demon, and smote lake and river with his icy mittens, so that when the sun rose next morning, lakes and streams were cased in a glittering armor of ice and the beavers were prisoners for the winter.

For the next four or five months they would live under ice, but they did not care about that. It was what they had planned and worked for for weeks. They were snugly housed with plenty of tender bark for their winter's food, so the wind might howl, and the frost freeze. It would only strengthen their barricade and make them more secure against the outer world.

In their thick-walled house it was quite snug. The heat of their bodies made it warm and the vent at the top carried off the foul air. Whenever they were tired of confinement, they would go for a swim in the pond through one of the three sub-marine passages, just as though the pond had not been frozen over. The only care that they needed to exercise was to look out that these holes did not ice over and thus lock them in their lodge like rats in a trap. To prevent this, they broke the ice frequently with their tails during cold days. Some cold nights they were obliged to watch the holes for hours to prevent them from freezing.

It was twilight of a bleak December day. The sun had taken his accustomed plunge behind the western horizon, but still shone blood red upon the clouds above the gray hills. There was still light enough from the afterglow to cast shadows, and phantom shapes peopled the aisles of the forest, or stretched their long arms across the fields.

The moon was just rising in the east, and it made shadows and shapes uncanny and unearthly. Already the heavens were studded with stars, and the wind moaned fitfully, rattling down snow and ice and whistling in the leafless twigs.

Down from the foothills, coming like a wary hunter, a wildcat prowled to the edge of the beavers' pond. A part of the way he had followed a rabbit's track, but it had proved so old that he had finally given it up. When he hurried he moved by quick jumps, bringing down all four feet at a time quite close together, and leaving those four telltale paw-prints in a bunch that hunters know so well. When he wanted to be more cautious, he walked cat-like, setting his fore paw down as softly as though his foot were velvet. He was an ugly looking brute, rather heavily built, with a thick head, and square topped club ears that usually lay back close to his head. His visage was generously sprinkled with whiskers, but it was accented by two hungry yellow green eyes, that seemed almost phosphorescent. His habitual expression was a snarl.

At the edge of the beaver pond, he tried the wind this way and that. His nostrils dilated, his eyes snapped fire, and his stump of a tail twitched. There was game abroad. He knew that scent of old. It was quite common away to the north from whence he had wandered. Cautiously he crept forward, putting down his paws in the dainty cat-like manner; but he must have known that the beavers were out of his reach at this time of year. Perhaps his hunger made him forgetful or he may have looked for the unexpected.

Half-way across the pond he stopped and sniffed again; it was close at hand now. Then he noticed the conical house on the island near, and crept cautiously toward it. Twice he walked about the house, which was now partly covered with snow, then with one jump he landed upon the very dome of the beavers' dwelling and peeked in at the air hole. What he saw made saliva drip from his mouth and his eyes dilate. There within three feet of his death-dealing paws were a pair of sleek beavers, warm and cozy. The hot scent fairly ravished his nostrils. It was unendurable, and he tore at the frozen mud house like a fury, first with his fore paws, then with his powerful hind paws armed with one of the best set of claws in the New England woods. But it was as hard as a stone wall and the beavers might just as well have been miles away as far as he was concerned.

Then the wildcat peeked in again, and ungovernable rage seized him. He reared upon his haunches, and beat the air with his fore paws and howled and shrieked like a demon. The beavers started from their twilight nap with sudden terror. This fury that was tearing at their house and filling the night with awful sounds seemed almost upon their very backs, so they fled precipitately through the water passages into the pond and took refuge in one of the burrows along the bank.

Tearing at their house and filling the night with awful sounds

A moment later when the wildcat again peeped in at the vent, the house was quite empty. Then after a few more futile efforts to break through the frozen walls he went away, going from bush to bush, alert and watchful. Only the tracks remained to tell that the beavers had had so unwelcome a caller.