ts shore; yet this pond is so remarkable
for its depth and purity as to merit a particular description. It is
a clear and deep green well, half a mile long and a mile and three
quarters in circumference, and contains about sixty-one and a half
acres; a perennial spring in the midst of pine and oak woods, without
any visible inlet or outlet except by the clouds and evaporation. The
surrounding hills rise abruptly from the water to the height of forty to
eighty feet, though on the southeast and east they attain to about one
hundred and one hundred and fifty feet respectively, within a quarter
and a third of a mile. They are exclusively woodland. All our Concord
waters have two colors at least; one when viewed at a distance, and
another, more proper, close at hand. The first depends more on the
light, and follows the sky. In clear weather, in summer, they appear
blue at a little distance, especially if agitated, and at a great
distance all appear alike. In stormy weather they are sometimes of a
dark slate-color. The sea, however, is said to be blue one day and green
another without any perceptible change in the atmosphere. I have seen
our river, when, the landscape being covered with snow, both water and
ice were almost as green as grass. Some consider blue "to be the color
of pure water, whether liquid or solid." But, looking directly down into
our waters from a boat, they are seen to be of very different colors.
Walden is blue at one time and green at another, even from the same
point of view. Lying between the earth and the heavens, it partakes of
the color of both. Viewed from a hilltop it reflects the color of the
sky; but near at hand it is of a yellowish tint next the shore where
you can see the sand, then a light green, which gradually deepens to a
uniform dark green in the body of the pond. In some lights, viewed
even from a hilltop, it is of a vivid green next the shore. Some have
referred this to the reflection of the verdure; but it is equally green
there against the railroad sandbank, and in the spring, before the
leaves are expanded, and it may be simply the result of the prevailing
blue mixed with the yellow of the sand. Such is the color of its iris.
This is that portion, also, where in the spring, the ice being warmed
by the heat of the sun reflected from the bottom, and also transmitted
through the earth, melts first and forms a narrow canal about the still
frozen middle. Like the rest of our waters, when m