The loon retires to solitary ponds to spend it.
The brine is pumped into conduits, carried to large ponds and there evaporated by the sun; during late years the salt has been refined here, being purified of the sulphates and magnesium compounds which formerly rendered it efflorescent and of a low commercial grade.
Flint's Pond, a mile eastward, allowing for the disturbance occasioned by its inlets and outlets, and the smaller intermediate ponds also, sympathize with Walden, and recently attained their greatest height at the same time with the latter.
The first dock (opened in 1846), the second (1859) and the third (1882) cover an area of '28 acres, with timber ponds of 44 acres and a total quayage of 2500 yards.
The sweet-flag Acorus Calamus, which occurs apparently wild in England in ditches, ponds, &c., is supposed to have been introduced.