I go slumping four or five inches in the snow on the river, and often into water above the ice, breaking through a slight crust under the snow, which has formed in the night. Each cold day is this concealed overflow, mixing with the snow beneath, is converted into ice, and so raises it, makes the surface snow shallower, and improves the walking; but unless it is quite cold, this snow and water is apt to get a slight crust only, through which you sink . . .