The origin of the Arch is very uncertain. It was unknown to the
Egyptians, for their chambers were roofed with long flat stones, and
sometimes the upper layers of stones form projections, so as to diminish
the roof surface. It is also supposed that it was unknown to the
Greeks, when they constructed their most beautiful temples, in the 5th,
4th, and 3d centuries B. C., as no structure answering to the true
character of the Arch has been found in any of these works. Minutoli has
given specimens of arches at Thebes; circular, and formed of four
courses of bricks, and it is maintained that these belonged to a very
ancient period, long before the Greek occupancy of that country. The
Macedonians were a civilized people long before the rest of the Greeks,
and were, in fact, their instructors; but the Greeks afterwards so far
excelled them that they regarded them as barbarians. Some say that
Etruria was the true birth-place of the Arch; it was doubtless from them
that the Romans learned its use. Tarquinius Priscus conquered the
Etrurians, and he it was who first introduced and employed the Arch in
the construction of the cloacæ, or sewers of Rome. The _cloaca maxima_,
or principal branch, received numerous other branches between the
Capitoline, Palatine, and Quirinal hills. It is formed of three
consecutive rows of large stones piled above each other without cement,
and has stood nearly 2,500 years, surviving without injury the
earthquakes and other convulsions that have thrown down temples,
palaces, and churches of the superincumbent city. From the time of
Tarquin, the Arch was in general use among the Romans in the
construction of aqueducts, public edifices, bridges, &c. The Chinese
understood the use of the Arch in the most remote times, and in such
perfection as to enable them to bridge large streams with a single span.
Mr. Layard has shown that the Ninevites knew its use at least 3000 years
ago; he not only discovered a vaulted chamber, but that "arched
gate-ways are continually represented in the bas-reliefs." Diodorus
Siculus relates that the tunnel from the Euphrates at Babylon, ascribed
to Semiramis, was vaulted. There are vaults under the site of the temple
at Jerusalem, which are generally considered as ancient as that edifice,
but some think them to have been of more recent construction, as they
suppose the Jews were ignorant of the Arch; but it is evident that it
was well known in the neighboring countries before the Jewish exile, and
at least seven or eight centuries before the time of Herod. It seems
highly probable, that the Arch was discovered by several nations in very
remote times.