winter shelter

First the shelter. He had to make the shelter coldproof and rainproof. That meant sealing the fire inside and closing the door in some way, but he thought the smoke would drive him out.
  Still, he thought, they did it. The people who came before him had tents and tipis and caves and they did not have stoves. So how did they do it?
  He took kindling into the shelter and made a small fire, and closed off the opening to see what would happen. As he had predicted, the smoke quickly filled the small enclosure and drove him coughing and spitting out into the air.
  He had to let the smoke out. They must have known a way — what did they do? Tipis just let it come out the top through a hole. He’d seen that in movies, old Westerns on television.
  Brian went to where his wall met the rock and made a hole about a foot across just above where he had made the fire, then tried it all again.
  This time when he closed the door and put some sticks on the fire it started to smoke again but as the heat developed it rose and carried a small draft through the hole in the ceiling. There was a moment of smoke; then it all magically cleared and Brian was sitting in a snug little hut with a fire warming his face. Clearly it would take only a small blaze to keep the little shelter warm, which meant less wood would be required.
  The side of the shelter was still far from airtight but about this Brian knew exactly what to do. He had spent one whole day watching a family of beaver mix mud and sticks to make a watertight dam. He spent three hours bringing up double armfuls of fresh mud from the lake to pack into the low wall with sticks and leaves. When he was done he covered it with another layer of brush to protect the mud and when it dried by nightfall he had a truly weathertight shelter. He still had to seal the door but that night he sat with a fire warming the inside of his home and knew that as long as he had wood — and he was living in the middle of a forest — he would stay warm no matter what kind of weather came. He slept so soundly that the bear could have come in again and torn the place apart and he would not have known it.
  In the morning he mudded the door and set it aside to dry and used more mud to make a seal on the wall, smooth and tight. Then he set back to work on the arrowhead problem.