channel bubbling out on the shore near Kangesentorre, about seven miles
to the north-west.

[Footnote 1: For the particulars of this singular well, see Vol. II. Pt.
IX. ch. vi. p. 536.]

A similar subterranean stream is said to conduct to the sea from another
singular well near Tillipalli, in sinking which the workmen, at the
depth of fourteen feet, came to the ubiquitous coral, the crust of which
gave way, and showed a cavern below containing the water they were in
search of, with a depth of more than thirty-three feet. It is remarkable
that the well at Tillipalli preserves its depth at all seasons alike,
uninfluenced by rains or drought; and a steam-engine erected at Potoor,
with the intention of irrigating the surrounding lands, failed to lower
it in any perceptible degree.

Other wells, especially some near the coast, maintain their level with
such uniformity as to be inexhaustible at any season, even after a
succession of years of drought--a fact from which it may fairly be
inferred that their supply is chiefly derived by percolation from the
sea.[1]

[Footnote 1: DARWIN, in his admirable account of the coral formations of
the Pacific and Indian oceans, has propounded a theory as to the
abundance of fresh water in the atolls and islands on coral reefs,
furnished by wells which ebb and flow with the tides. Assuming it to be
impossible to separate salt from sea water by filtration, he suggests
that the porous coral rock being permeated by salt water, the rain which
falls on the surface must sink to the level of the surrounding sea, "and
must accumulate there, displacing an equal bulk of sea water--and as the
portion of the latter in the lower part of the great sponge-like mass
rises and falls with the tides, so will the fresh water near the
surface."--_Naturalist's Journal_, ch. xx. But subsequent experiments
have demonstrated that the idea of separating the salt by filtration is
not altogether imaginary; as Darwin seems to have then supposed; and Mr.
WITT, in a remarkable paper _On a peculiar power possessed by Porous
Media of removing matters from solution in water_, has since succeeded
in showing that "water containing considerable quantities of saline
matter in solution may, by merely percolating through great masses of
porous strata during long periods, be gradually deprived of its salts
_to such an extent as probably to render even sea-water
fresh_."--_Philos. Mag_., 1856. Divesting the subject therefore o