mark with surprising accuracy.

In the fall of 1878 I observed that he built unusually high and massive
nests. I noticed them in several different localities. In a shallow,
sluggish pond by the roadside, which I used to pass daily in my walk,
two nests were in process of construction throughout the month of
November. The builders worked only at night, and I could see each day
that the work had visibly advanced. When there was a slight skim of ice
over the pond, this was broken up about the nests, with trails through
it in different directions where the material had been brought. The
houses were placed a little to one side of the main channel, and were
constructed entirely of a species of coarse wild grass that grew all
about. So far as I could see, from first to last they were solid masses
of grass, as if the interior cavity or nest was to be excavated
afterward, as doubtless it was. As they emerged from the pond they
gradually assumed the shape of a miniature mountain, very bold and steep
on the south side, and running down a long gentle grade to the surface
of the water on the north. One could see that the little architect
hauled all his material up this easy slope, and thrust it out boldly
around the other side. Every mouthful was distinctly defined. After they
were two feet or more above the water, I expected each day to see that
the finishing stroke had been given and the work brought to a close. But
higher yet, said the builder.

December drew near, the cold became threatening, and I was apprehensive
that winter would suddenly shut down upon those unfinished nests. But
the wise muskrats seemed to know better than I did. Finally, about the
6th of December, the nests assumed completion; the northern incline was
absorbed or carried up, and each structure became a strong massive cone,
three or four feet high, the largest nest of the kind I had ever seen.
"Does it mean a severe winter?" I inquired. An old farmer said it meant
"high water," and he was right once, at least, for in a few days
afterward we had the heaviest rainfall known in this section for half a
century. The creeks rose to an almost unprecedented height. The sluggish
pond became a seething, turbulent watercourse; gradually the angry
element crept up the sides of these lake dwellings, till, when the rain
ceased, about four o'clock, they showed above the flood no larger than a
man's hat. During the night the channel shifted till the main current
swept ove