Before the lake-bed was snow-covered, all the numerous canals and basins which the beaver had excavated could be plainly seen and examined. The magnitude of the work which the beaver had performed in making these is beyond comprehension. I took a series of photographs of these excavations and made numerous measurements. To the north of the house a pool had been dug that was three feet deep, thirty feet long, and about twenty wide. There extended from this a canal that was one hundred and fifty feet long. The food basin was thirty feet wide and four feet deep. This had a canal connection with the house. In the bottom of the basin was one of the feeble springs which supply the lake. Another canal, which extended three hundred and fifty feet in a northerly direction from the house, was from three to four feet wide and three feet deep. The largest ditch or canal was seven hundred and fifty feet long and three feet deep throughout. This extended eastward, then northeasterly, and for one hundred feet was five feet wide. In the remaining six hundred and fifty feet it was three to four feet wide. There were a number of minor ditches and canals connecting the larger ones, and altogether the extent of all made an impressive show in the empty lake-basin. Meantime the old beaver had a hard winter. The cold weather persisted, and finally the well in which he had deposited winter food froze to the bottom. Even the entrance-holes into the house were frozen shut. This sealed him in. The old fellow, whose teeth were worn and whose claws were bad, apparently tried in vain to break out. On returning from three months' absence, two friends and I investigated the old beaver's condition. We broke through the frozen walls of the house and crawled in. The old fellow was still alive, though greatly emaciated. For some time--I know not how long--he had subsisted on the wood and the bark of some green sticks which had been built into an addition of the house during the autumn. We cut several green aspens into short lengths and threw them into the house. The broken hole was then closed. The old fellow accepted these cheerfully. For six weeks aspens were occasionally thrown to him, and at the end of this time the spring warmth had melted the deep snow. The water rose and filled the pond and unsealed the entrance to the house, and again the old fellow emerged into the water. The following summer he was joined, or rejoined, by a number of other beaver.