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.
