Although the pond is commonly covered with snow, or the ice curtained with air bubbles, there have been numerous times during which I have had clear views into the water, and could see and enjoy all that was going on within, as completely as though looking at fish or turtles through the glass walls of an aquarium. Often I have peered through the ice which covered the most used place of a winter beaver pond,--the area between the house-entrance and the food-pile. The thinness of the ice over this place was maintained by spring-water which came up through the bottom, and the beaver had so arranged their affairs that they made the best use of this shallow-freezing water. Of course most ponds are without springs. Many a time I have seen a beaver come out of the doorway of his house and go swimming toward the food-pile with his hands against his breast. At the pile, if there was nothing small or short enough, he set to work and gnawed it off. The piece secured was taken into the doorway either in his hands or in his teeth. Afterward a beaver--the same one, I suppose--came out of the doorway, and cast the clean bone of the stick, from which the bark had been eaten, into the bottom of the pond. When there is nothing else to do, the beaver apparently comes into the pond a few times each day for a swim. In the midst of swimming he rises at times to the under surface of the ice and, with his nose against it, exhales a quantity of air. After remaining with nose at this point a few seconds, the action of the air bubbles indicates that he is inhaling the purified air. The rootstocks of the water-lily are sometimes dug from the bottom of the pond. At other times the beaver eats the stalks of plants that grow in the water, or digs out willow or other roots around the edge of the pond. Numbers of trout frequently lie in the water close to the doorway of a beaver house or around the food-pile. Possibly the beaver dispense tidbits of food that are liked by the trout. Occasionally grubs fall from the holes in wood from which beaver have eaten the bark. While beaver are digging in the bottom of the pond they doubtless unearth food-scraps that are welcome to trout, for these often hover in numbers on the outskirts of the muddy water which beaver roil while digging. Although it appears that beaver have dull winters with but little to do but eat, sleep, and swim, it is probable that some of their time is spent at work. A part of their tunneling and pond-bottom canal-digging is done in winter. I have known of their extending canals in the bottom of the pond and making submarine tunnels while the pond was ice-covered.