Walden, for instance--one might suppose that is was called, originally,
_Walled-in_ Pond.

The pond was my well ready dug. For four months in the year its water is
as cold as it is pure at all times; and I think that it is then as good
as any, if not the best, in the town. In the winter, all water which is
exposed to the air is colder than springs and wells which are protected
from it. The temperature of the pond water which had stood in the room
where I sat from five o'clock in the afternoon till noon the next day,
the sixth of March, 1846, the thermometer having been up to 65° or 70°
some of the time, owing partly to the sun on the roof, was 42°, or one
degree colder than the water of one of the coldest wells in the village
just drawn. The temperature of the Boiling Spring the same day was 45°,
or the warmest of any water tried, though it is the coldest that I know
of in summer, when, besides, shallow and stagnant surface water is not
mingled with it. Moreover, in summer, Walden never becomes so warm as
most water which is exposed to the sun, on account of its depth. In the
warmest weather I usually placed a pailful in my cellar, where it became
cool in the night, and remained so during the day; though I also
resorted to a spring in the neighborhood. It was as good when a a week
old as the day it was dipped, and had no taste of the pump. Whoever
camps for a week in summer by the shore of a pond, needs only bury a
pail of water a few feet deep in the shade of his camp to be independent
of the luxury of ice.

There have been caught in Walden, pickerel, one weighing seven pounds,
to say nothing of another which carried off a reel with great velocity,
which the fisherman safely set down at eight pounds because he did not
see him, perch and pouts, some of each weighing over two pounds,
shiners, chivins or roach (_Leucisus pulchellus_), a very few breams,