While visiting ponds at the beginning of winter, I have many times noticed that, shortly after the pond was solidly frozen over, a hole was made through the dam just below the water-surface of the pond. This lowered the water-level two inches or more. Did this slight lowering of the water have to do with the ventilation of the ice-covered pond, or was it to put a check on deep freezing, or for both purposes? In the majority of cases these holes were made from ponds which, during the winter, received but a meagre inflow of fresh water. Naturally, ponds receiving a strong inflow of water would be better ventilated, and would freeze less swiftly and deeply than those whose waters became stagnant. This drawing-off of water after a few inches of ice had formed, would, in some places, despite the settling of the ice, form an air blanket that would delay freezing, and thus possibly prevent the ice from forming so thickly. The air admitted by drawing off the water would be inclosed beneath the ice, and might thus be helpful to the beaver inclosed in house and pond. In only a few cases were these holes made from ponds which had subway tunnels,--tunnels which run from alongside the house through the bottom of the pond to a point above water-level on the shore. In a few instances the beaver, I do not know how many, came out of this hole, cut and ate a few twigs, and then returned and closed it. Twice this was used as a way out by beaver who emerged and went to other colonies. In one case the beaver entered the other pond by making a hole through the dam. In the other they entered the pond through a subway tunnel. While these holes which lower the pond-level may have chiefly to do with ventilation, or may be for the purpose of putting a check on freezing, my evidence is not ample enough for final conclusions. A sentence of close confinement for about a third of the year for an animal that breathes air and uses pure water, is simply one of the strange ways that work out with nature. While winter lasts, a beaver must spend his time either in the dark, ill-ventilated house or in the water of the pond. Apparently he does much sleeping and possibly has a dull time of it. No news, no visitors, and apparently nothing to do! Still a beaver has food, and when dangers surround the wild folk outside the pond's roof of glass, he would be considered a good risk for life insurance.