In the structures of the ancients, the hardness of their cement equals
that of marble itself. The firmness of their highways has never been
equalled. Some were paved with large blocks of black marble. Their
bridges, some of which still remain, are indubitable monuments of the
greatness of their conceptions. The Roman bridge at Gard, near Nismes,
is one of them. It serves at once as a bridge and an aqueduct, goes
across the river Gardon, and connects two mountains, between which it is
enclosed. It comprehends three stories; the third is the aqueduct, which
conveys the waters of the Eure into a great reservoir, to supply the
amphitheatre and city of Nismes. Trajan’s bridge over the Danube had
twenty piers of free-stone, some of which are still standing, a hundred
and fifty feet high, sixty in circumference, and distant one from
another a hundred and seventy.
Among the ornaments and conveniences of ancient buildings was glass.
They decorated their rooms with glasses, as mirrors. They also glazed
their windows, so as to enjoy the benefit of light, without being
injured by the air. This they did very early; but before they discovered
that manner of applying glass, the rich made use of transparent stones
in their windows, such as agate, alabaster, phengifes, talc, &c.