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Scientific American Supplement, No. 520, December 19, 1885 by Various
page 59 of 123 (47%)
arches were constructed of transverse arches themselves. The work
consisted of concrete, formed with Roman cement so hard that it turns the
points of pickaxes when employed against it, with layers of tiles at
regular intervals. The surface of the concrete is covered with small
cubical blocks of stone placed so that their diagonals are horizontal and
vertical, and forming what is known as _opus reticulatum_. After crossing
the bridge the pipes were carried up the other side of the valley into a
reservoir, of which little remains, and then the aqueduct was continued
to the next valley, passing over three bridges in its course. This
valley, that of St. Irenée, is much smaller than either of the others,
but nevertheless it was deep enough to necessitate the construction of
inverted siphons, of which there were eight. Leaving the reservoir on the
other side of this valley, the aqueduct was carried on a long bridge (the
twentieth on its course) which crossed the plateau on the top of
Fourvieres and opened into a large reservoir, the remains of which are
still to be seen on the top of that hill.

From this reservoir, which was 77 ft. long and 51 ft. wide, pipes of lead
conveyed the water to the imperial palace and to the other buildings near
the top of the hill. Some of these lead pipes were found in a vineyard
near the top of Fourvieres at the beginning of the eighteenth century,
and were described by Colonia in his history of Lyons. They are made of
thick sheet lead rolled round so as to form a tube, with the edges of the
sheet turned upward, and applied to one another in such a way as to leave
a small space, which was probably filled with some kind 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 Cæsar), 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
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