strata-seams, sometimes these open so wide
as to form caverns ; let ns suppose one of
these caverns at h closed at the bottom,
into which the water is constantly infiltering
from the seams; suppose a crack or
transverse seam c passes from the cavern
to the next strata-seam above at d, along
which there is an interstice downwards to
an aperture at e ; as these mountains are
traversed by cross seams nearly as regular
as those of the stratification, all the conditions
here stated may well be supposed
to occur. Now, whenever the water in the
cavern rises above the level of the crack c,
it will descend down the seam to e, and the
pressure of the atmosphere acting on the
surface of the water in the cavern, will
force it along the passage, until a communication
takes place between the air above,
and the air below the water. In rainy
weather, it is obvious that the water will
be infiltered into the cavern more rapidly,
and produce more frequent intermissions,
particularly as the edges of the strata are
exposed to the direct action of the rain.
In returning from Haute Combe, we
kept on the western side of the lake, to
see several cascades that fall into it near the
ruins of Chateau Bourdeaux. When upon
the lake, or at the upper end of it, there is
a fine view of the mountains south of
Chamberry, and beyond these, the snowy
summits of the Cottian Alps bound the
horizon. The immediate scenery round
this end of the lake is also extremely rich
and varied, though the meadow which terminates
it is marshy ; I have before remarked,
it has once been part of the lake.
We made another excursion to Grisey,
a small village four miles from Aix, on the
high road to Geneva, to visit a waterfall,
which is much spoken of from the melancholy
fate of a young lady, who fell into the
torrent a few years since, in presence of
her friend, the Queen of Holland, and her
suite. A river has here excavated a profound
ravine in a rock of limestone, which
is, in fact, a hard and nearly white marble.
In rainy seasons, before falling into the ravine,
the water spreads over a broad floor
of this limestone, but at other times, when
the river is not so full, it pours along a
number of deep narrow channels, and is
seen at a great depth, boiling, foaming, and
L 2
a