ader must be referred for further
details to the work of Mr. Scrope. I shall content myself with some
further reference to the central figure in this grand chain, the Puy de
Dome itself.

_Ascent of the Puy de Dome._--On ascending by the winding path up the
steep side of the mount, and on reaching the somewhat flattened summit,
the first objects which strike the eye are the massive foundations of
the Roman temple of Mercury; they are hewn out of solid grey lava,
altogether different from the rock of the Puy de Dome itself, which must
have been obtained from one of the lava-sheets of the Mont Dore group.
To have carried these large blocks to their present resting-place must
have cost no little labour and effort. The temple is supposed to have
been surmounted by a colossal statue of the winged deity, visible from
all parts of the surrounding country which was dedicated to his honour,
and the foundations were only discovered a few years ago when excavating
for the foundation of the observatory, which stands a little further on
under the charge of Professor Janssen. On proceeding to the northern
crest of the platform a wonderful view of the extinct craters and
domes--about forty in number, and terminating in the Puy de Beauny, the
most northerly member of the chain--is presented to the spectator. To
the right is the Vale of Clermont and the rich valley of the Allier
merging into the great plain of Central France. On the south side of the
platform a no less remarkable spectacle meets the eye. The chain of Puys
and broken craters stretches away southwards for a distance of nearly
ten miles, while the horizon is bounded in that direction by the lofty
masses of the Mont Dore, Cantal, and Le Puy ranges. Nor does it require
much effort of the imagination to restore the character of the region
when these now dormant volcanoes were in full activity, projecting
showers of ashes and stones high into the air amidst flames of fire and
vast clouds of incandescent gas and steam.

The material of which the Puy de Dome is formed consists of a light
grey, nearly white, soft felsitic lava, containing crystals of mica,
hornblende, and specular iron-ore. It is highly vesicular, and was
probably extruded in a pasty condition from a throat piercing the
granitic plateau and the overlying sheet of ancient lava of Mont Dore.
It has been suggested that such highly felsitic and acid lavas as that
of which the Puy de Dome, the Grand Sarcoui, and Clie