As I was desirous to recover the long lost bottom of Walden Pond, I surveyed it carefully, before the ice broke up, early in ’46, with the compass and chain and sounding line . . . The greatest depth was exactly one hundred and two feet; to which may be added the five feet which it has risen since, making one hundred and seven.(Walden, 315-316)Thoreau’s survey of Walden Pond, 1846, as published in Walden; or, Life in the Woods (Boston: Ticknor & Fields, 1854)