of cement. These
pipes, of which it is said that twenty or thirty, each from 15 ft. to 20
ft. long, were found, were marked with the initial letters TI. CL. CAES.
(Tiberius Claudius Caesar), and afford positive evidence that the work was
carried out under the emperor Claudius. Lead pipes, constructed in a
similar manner, have also been found at Bath, in this country, in
connection with the Roman baths. The great difference between this
aqueduct and those near Rome arises from the fact that, instead of being
carried across a nearly flat country, it was carried across one
intersected with deep ravines, and that it was therefore necessary to
have recourse to the system of inverted siphons. There can be no doubt
that the inverted siphons were made of lead, although no remains of them
have been found; for we know that the Romans used lead largely, and, as
we have seen, pieces of the lead distribution pipes have been found. It
is possible, and even likely, that strong cords of hemp were wound round
the pipes forming the siphons, as is related by Delorme in describing a
similar Roman aqueduct siphon near Constantinople; Delorme also
describes, in the aqueduct last mentioned, a pipe for the escape of air
from the lowest part of the siphon carried up against a tower, which was
higher than the aqueduct, and it is certain that there must have been
some such contrivance on the siphons of the aqueduct constructed at
Lyons.

Flacheron supposes that they consisted of small pipes carried from the
lowest part of the siphons up along the side of the valley and above the
reservoirs, or, in some instances, of taps fixed at the lowest part of
the siphons. The Romans have been blamed for not using inverted siphons
in the aqueducts at Rome, and it has been said that this is a sufficient
proof that they did not understand the simplest principles of hydraulics,
but the remains of the aqueducts at Lyons negative this assumption
altogether. The Romans were not so foolish as to construct underground
siphons, many miles long, for the supply of Rome; but where it was
necessary to construct them for the purpose of crossing deep valleys,
they did so. The same emperor Claudius who built the aqueduct at Rome
known by his name built the aqueduct of Mont Pila, at Lyons, and it is
quite clear, therefore, that his engineers were practically well
acquainted with the principles of hydraulics. It is thus seen that the
ancient Romans spared no pains to obtain