So, while I shivered in the searching east wind on the sky side of the ice, the muskrats were well fed and comfortable in a region of even higher temperature, a country where the spring, which we say comes up out of the south, but the muskrat knows wells up out of the ground beneath, is already at his door. Its warmth is in the bog below and has softened and even melted the ice all about the tepees. The ice on the pond is a foot thick still, but the water beneath it is thrilled with this same potency and you have but to stir it to sniff its fragrance. Below the pond the brook which is its outlet splashes over the long-abandoned sills of what was a gristmill dam in the days of the early settlers. Here in spite of the keen lances of the wind and its roar in the frozen maples overhead, I heard the soft tones of the coming season in every babble of the brook. All the air was full of a fresh, inviting fragrance which the water gives off as it flows. All the pond is full of it beneath the ice already, and the muskrat breathes it in his every excursion under the crystal depths. Soon he will abandon the winter houses, which as soon as the frost leaves them will sag and flatten and begin to sink into the bog itself, building its outer edge a little firmer here and there, and thus helping it in its yearly encroachment on the pond itself. As the ages have gone by, Mussascus has been a pretty potent factor in this encroachment. As the beaver has been a maker of ponds and a conserver of streams, holding and delaying their waters with his dams, so the muskrat has helped in the making of meadows and the sanding and grading of pond edges. The first is done by his winter nests, the second by his summer burrows which start under water at the pond edge and slant along near the surface for thirty to fifty feet. Many cubic yards of sand and loam are dug from these burrows and spread along in the shallows. His river habits are strong upon him in this work, for he usually makes a delta of entrances, three or four leading up into the same passage which often has a wee exit above water, near the edge. Here if you are particularly fortunate you may in midsummer see his young poke their noses up, longing for a peek at the great world, before they are big enough to swim out into it. Here, too, weasel and mink sometimes find entrance and devour his family. But there are three litters a year, as a rule, so the occasional weasel serves to keep down a too great increase in the population.