e distinct sheets of water were intersected in a well, and
from each of these a supply obtained. In the third waterbearing stratum,
at the depth of 150 feet, a cavity was found in which the borer fell
suddenly about a foot, and thence the water ascended in great
volume.[311] The same falling of the instrument, as in a hollow space,
has been remarked in England and other countries. At Tours, in 1830, a
well was perforated quite through the chalk, when the water suddenly
brought up, from a depth of 364 feet, a great quantity of fine sand,
with much vegetable matter and shells. Branches of a thorn several
inches long, much blackened by their stay in the water, were recognized,
as also the stems of marsh plants, and some of their roots, which were
still white, together with the seeds of the same in a state of
preservation, which showed that they had not remained more than three or
four months in the water. Among the seeds were those of the marsh plant
_Galium uliginosum_; and among the shells, a freshwater species
(_Planorbis marginatus_), and some land species, as _Helix rotundata_,
and _H. striata_. M. Dujardin, who, with others, observed this
phenomenon, supposes that the waters had flowed from some valleys of
Auvergne or the Vivarais since the preceding autumn.[312]

An analogous phenomenon is recorded at Reimke, near Bochum in
Westphalia, where the water of an Artesian well brought up, from a
depth of 156 feet, several small fish, three or four inches long, the
nearest streams in the country being at a distance of some leagues.[313]

In both cases it is evident that water had penetrated to great depths,
not simply by filtering through a porous mass, for then it would have
left behind the shells, fish, and fragments of plants, but by flowing
through some open channels in the earth. Such examples may suggest the
idea that the leaky beds of rivers are often the feeders of springs.

MINERAL AND THERMAL SPRINGS.

Almost all springs, even those which we consider the purest, are
impregnated with some foreign ingredients, which, being in a state of
chemical solution, are so intimately blended with the water as not to
affect its clearness, while they render it, in general, more agreeable
to our taste, and more nutritious than simple rain-water. But the
springs called mineral contain an unusual abundance of earthy matter in
solution, and the substances with which they are impregnated correspond
remarkably with those evolved