t h e PASSAGE OP HANNIBAL
Hannibal passed with his army into Italy
by the upper valley of the Isere, and the
Little St. Bernard. Nothing but an actual
inspection of the route, can give an adequate
idea of the difficulties he must have
had to encounter when he entered this
defile, which is forty miles in length, and
defended by many formidable passes, where
a few men, placed on the heights above,
might have successfully resisted the most
powerful armies.
The account given by some historians,
of Hannibal’s dissolving the rocks by vinegar,
in his passage over the Alps, appears
so improbable, that it has generally been
treated, in modern times, as a fable, undeserving
attention. An inspection of the
route, however, inclined me to believe that
this story, like many ancient fables, was
founded on facts that have been perverted
by the ignorance of historians. In many
of the passes in the valley of the Isere,
where the rocks overhang the river on
each side, a path carried midway along the
side of the precipice might be so obstructed
by a projecting mass of stone, as
to deny access to oxen or elephants. Now,
in such situations, it will be readily admitted
that a small quantity of gunpowder
would effect more in a few hours than the
labour of men for several days, especially
as, from the narrowness of the pass, not
more than one or two men could work at the
same time. We are unacquainted with the
means which the ancients employed in
breaking and removing large masses of
stone; it is possible that the expansive
power of vapour might be one of them.
Thus by boring hard calcareous rocks, and
filling the cavity with concentrated vinegar,
and plugging up the aperture, they might,
by the evolution of gas, obtain a similar
effect to the explosion of gunpowder, or
the expansion of steam ; this effect might
be farther increased by making a large fire
against the rock. Count Bumford ascertained
that a dram of water, inclosed in a
mass of iron the size of a solid twenty-four
pound cannon, was sufficient to burst it,
with a tremendous explosion on the application
of heat: even the expansion of
water by freezing will rend the hardest
rocks. It also deserves attention, that
most of the calcareous strata in the Alps
are intersected by cross seams, evidently
the result of crystallization in the mass,
p 2
kI—-
Ml
1 •^1