These rare and singular works of excavation are called beaver canals. One of these, which was the largest that was known to occur in this part of Michigan, I examined with the utmost attention. It was an open trench or channel, about half a mile long, two to three feet wide, and from one to two feet deep. The bottom was of the same width as the surface, the sides being perpendicular. It connected a large pond with the adjacent forest. The canal was sufficiently large to give room for a beaver to swim in it and push in front of him the cutting of birchwood that was to be conveyed to the lodge and there stored for the winter supply of food. The depth was enough for the purpose of concealment. I also examined some other canals connecting the ponds with trees, which were of a different character and much smaller. The Indians were of opinion that these must have been made exclusively for escape when the beavers, whilst at work, were suddenly alarmed. But the most important results of the actions of the beavers are the alterations made by them in the aspect of the country, in consequence of their raising the levels of the water and causing large spaces of land to be subject to overflow. Thus, when the dams are in order and efficiently maintained, much of the adjoining land, when it lies low, becomes a swamp and the trees decay and fall. Then if the works are neglected and the waters follow their usual direction, the lands become dry and are changed into fertile grass meadows. Some of these meadows are of considerable extent. Around Ishpeming they supply the fodder required for the cattle employed at the mines. One of them, which occupies a large acreage, yields over fifty tons of hay annually. An explorer who happened to pass through a region of this nature after it had been deserted by the beavers, would be surprised, when following the trail through the forest, to find himself entering into one of these open spaces, which have the appearance of small savannahs, and he would be unable to understand how such sharply defined inclosures could have been formed. Near the borders of the meadows and ponds, several birches were undergoing the process of being felled. The operations were extremely curious, and it was evident that the beavers are both careful and ingenious in the execution of the work.