Bakewell’s Travels in the Tarentaise, §c. 
vine, I obseryed the lime-stone strata 
on the left were perpendicular. The 
limestone here is subcrystalline, and 
extremely hard, but it is as much shat- 
tered as some of the chalk rocks in 
Kent. The road, after continuing a 
few miles between rocks of limestone, 
through which it appears to have been 
cut, is suddenly closed by a natural 
wall of rock, at least 800 feet in height, 
which seems to bar all farther progress. 
It is through, this rock that an archway 
has been perforated, 27 feet in breadth, 
as many in height, and 960 feet iu 
length. We were five minutes in pass- 
ing through it, but, instead of the bare 
and rocky ravine we had just left, a 
rich extended vale, surrounded by mag- 
nificent mountains, burst in an instant 
on our view, as if by enchantment. 
The galleries cut through the rocks 
on the Semplon route produce vo sur- 
prise, for, before entering them, you 
discover what the scene will be when 
you are passed through, but the tra- 
veller who arrives at the passage’ of les 
Echelles from Chamberry, sees nothing 
on his approach but barren precipices, 
that seem ‘the confines of the habitable 
world; when, after a few minutes of 
gloomy twilight, villages, churches, 
cornfields, vineyards, and forests, are all 
before him, bounded by a range of 
mountains, whose sides are covered 
with verdure, though their summits are 
capped with perpendicular walls and 
turrets of limestone of amazing height. 
On the farthest of these mountains, the 
monastery of the Grand Chartreuse is 
situated, but it cannot be seen from the 
road. The western opening of the pas- 
sage is considerably above the bottom 
of the valley, and we descended gra- 
dually for two miles before we arrived 
at les Echelles, a frontier town on the 
borders of Savoy, where we dined. On 
our return, I examined the passage and 
the rocks with more attention, The 
gallery, or archway, is cut through a 
very indurated limestone, susceptible of 
a high polish; it was perforated by 
blasting. Both ends were opened at 
the same time, and the labour was con- 
tinued by different relays of men, work. 
ing day and night for three years, until 
the excavations on each side were 
united. Near the entrance of the pas- 
sage I met with a very intelligent man, 
superintending the repairs of the road, 
He had worked at the gallery, and he 
informed me that when the excavations 
from each end nearly met, and the thin 
partilion of rock between them was 
Q 
587 
first broken through by the stroke .of 
the pick, a deep and lond explosion 
followed, resembling thunder. The 
cause of this explosion is easily ex- 
plained. The air on the eastern side of 
the mountain, or rather wall of rock, 
through which the passage is cut, must 
frequently be many degrees colder, and 
of course denser than that on tlie western 
side, as it is sheltered botb in the south 
and west from the sun’s, rays in the af- 
ternoon. The mountain rises full one 
thousand feet above the passage, and at 
least fifteen hundred feet above the bottom 
of the valley, forming a partition between 
the hot air of the valley and the cool air in 
the ravine, or Cul de Sac, on the eastern 
side. Now a sudden opening being 
made. for the dense air to rash into 
a rarer medium must necessarily pro- 
duce a loud report, on the same princi- 
ple as a report is made by the bursting 
of a bladder in the receiver of an-air 
pump, when the air that surrounds it is 
rarified. The sound of the explosion 
would be greatly incrcased by rever- 
beration through the long archyay on 
each side. 
The rock is so firm that the archway 
appears to be in no danger of injury 
from any natural cause, less powerful 
than an earthquake: it will Jong re- 
main a monument of the genius of 
Napoleon, Travellers who visit. the 
passage of les Echelles for the scenery, 
should approach it from Chamberry, 
and not, from the western or’ Lyons 
side. On the one side you emerge fiom, 
the earth to behold a sudden vision of 
glory ; on the other you leave a splendid 
valley to plunge into a caye, that opens 
only on barren rocks. I have mentioned 
that the rock through which the per- 
foration is made, appears to bar all 
farther access, and the inhabitants of 
this valley and the adjoining parts of 
Dauphiny had, in early ages, no direct 
natural Communication with the other 
parts of Savoy. On the left, or south 
side of the ravine, just before you arrive 
at the gallery, there is a deep fissure 
between the rocks, which entends for 
half a league, and turns round towards 
the valley. Formerly persons on foot 
were accustomed to pass along this 
‘fissure, till they came to a natural ca- 
vern, or series of caverns, which lead to 
an aperture looking into the valley, and 
a communication was formed with it by 
steps and ladders, made tor the purpose 
of descending from this opening down 
the perpendicular face of rock into the 
valley; hence the road obtained its 
name, 
