Some who have lain flat on the ice for a long time, looking down through the illusive medium, perchance with watery eyes into the bargain, and driven to hasty conclusions by the fear of catching cold in their breasts, have seen vast holes "into which a load of hay might be driven," if there were anybody to drive it, the undoubted source of the Styx and entrance to the Infernal Regions from these parts. Others have gone down from the village with a "fifty-six" and a wagon load of inch rope, but yet have failed to find any bottom; for while the "fifty-six" was resting by the way, they were paying out the rope in the vain attempt to fathom their truly immeasurable capacity for marvellousness. But I can assure my readers that Walden has a reasonably tight bottom at a not unreasonable, though at an unusual, depth. I fathomed it easily with a cod-line and a stone weighing about a pound and a half, and could tell accurately when the stone left the bottom, by having to pull so much harder before the water got underneath to help me. 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. This is a remarkable depth for so small an area; yet not an inch of it can be spared by the imagination. What if all ponds were shallow? Would it not react on the minds of men? I am thankful that this pond was made deep and pure for a symbol. While men believe in the infinite some ponds will be thought to be bottomless. A factory-owner, hearing what depth I had found, thought that it could not be true, for, judging from his acquaintance with dams, sand would not lie at so steep an angle. But the deepest ponds are not so deep in proportion to their area as most suppose, and, if drained, would not leave very remarkable valleys. They are not like cups between the hills; for this one, which is so unusually deep for its area, appears in a vertical section through its centre not deeper than a shallow plate. Most ponds, emptied, would leave a meadow no more hollow than we frequently see. William Gilpin, who is so admirable in all that relates to landscapes, and usually so correct, standing at the head of Loch Fyne, in Scotland, which he describes as "a bay of salt water, sixty or seventy fathoms deep, four miles in breadth," and about fifty miles long, surrounded by mountains, observes, "If we could have seen it immediately after the diluvian crash, or whatever convulsion of nature occasioned it, before the waters gushed in, what a horrid chasm must it have appeared!

"So high as heaved the tumid hills, so low
Down sunk a hollow bottom broad and deep,
Capacious bed of waters."

But if, using the shortest diameter of Loch Fyne, we apply these proportions to Walden, which, as we have seen, appears already in a vertical section only like a shallow plate, it will appear four times as shallow. So much for the increased horrors of the chasm of Loch Fyne when emptied. No doubt many a smiling valley with its stretching cornfields occupies exactly such a "horrid chasm," from which the waters have receded, though it requires the insight and the far sight of the geologist to convince the unsuspecting inhabitants of this fact. Often an inquisitive eye may detect the shores of a primitive lake in the low horizon hills, and no subsequent elevation of the plain have been necessary to conceal their history.