So all through the stilly night they worked, and, when the day broke, they sought the deep water and certain holes under the banks wherein to rest. But before he left the dam, the wise old leader examined the work all over to make sure that it was right. When the first shadows crept forth late the next afternoon, the old leader was the first back on the work. One by one the others joined him, and another night of labor had begun. Some cut trees and saplings, some hauled them to the dam, and some dug up turf and mud and piled it on the dam. There was no talking. Everybody was too busy to talk. [Illustration: SOME CUT TREES AND SAPLINGS, SOME HAULED THEM TO THE DAM] Most of Tommy’s companions had helped build dams before and knew just what to do. Tommy asked no questions, but did as the others did. Slowly the dam grew higher, and Tommy noticed that the brook was spreading out into a pool; for the water came down faster than it could work its way through that pile of poles and brush. Twigs, and leaves, and grass floated down from the places higher up where the beavers were at work, and, when these reached the dam, they were carried in amongst the sticks by the water and lodged there, helping to fill up the holes and hold the water back. As night after night the dam grew higher and the pool behind it grew broader and deeper, Tommy began to take pride in his work. He no longer thought of play but was as eager as the others to complete the dam. The stars looked down from the soft sky and twinkled as they saw the busy workers. At last the dam was completed, for the time being at least. Very thoroughly the wise old leader went all over it, inspecting it from end to end; and when he was satisfied, he led his band to one side of the little pond formed by the dam, and there he chose a site for the house wherein they would spend the winter. First a platform of sticks, and mud, and turf was built until it was a few inches above the water. Then began the raising of the walls, a mass of brush and turf until the walls were three feet thick and so solid that Jack Frost would find it quite useless to try to get inside. The roof was in the shape of a rough dome and at the top was comparatively thin; here little or no mud was used, so that there were tiny air-holes, for, like all other warm-blooded animals, a beaver must breathe. Within, was a comfortable room of which the platform was the floor. From this, two burrows, or tunnels, led down on the deep-water side, one of these being on a gradual incline, that food sticks might the easier be dragged in. The entrances to both were at the very bottom of the pond, where there would be no danger of them being closed by ice when the pond should freeze in winter. These were the only entrances, so that no foe could reach them unless he were able to swim under water, and there were no such swimmers whom they had cause to fear.