away the
superincumbent stones at an angle of about 45 deg. with the horizon.

Of the different forms and curves of arches now in use, the only one
adopted by the Romans was the semicircle; and the use of this
constitutes one leading distinction between Greek and Roman
architecture, for by its application the Romans were enabled to execute
works of far bolder construction than those of the Greeks: to erect
bridges and aquaeducts, and the most durable and massive structures of
brick. On the antiquity of the arch among the Egyptians, Mr. Wilkinson
has the following remarks: "There is reason to believe that some of the
chambers in the pavilion of Remeses III., at Medeenet Haboo, were
arched with stone, since the devices on the upper part of their walls
show that the fallen roofs had this form. At Saggara, a stone arch
still exists of the time of the second Psamaticus, and, consequently,
erected six hundred years before our era; nor can any one, who sees the
style of its construction, for one moment doubt that the Egyptians had
been long accustomed to the erection of stone vaults. It is highly
probable that the small quantity of wood in Egypt, and the consequent
expense of this kind of roofing, led to the invention of the arch. It
was evidently used in their tombs as early as the commencement of the
eighteenth dynasty, or about the year 1540 B.C.; and, judging from some
of the drawings at Beni Hassan, it seems to have been known in the time
of the first Osirtasen, whom I suppose to have been contemporary with
Joseph."--_Manners and Customs of the Anc. Egyptians_, vol. ii., p.
116, 117, 1st series.

The entrance to the great Pyramid at Gizeh is somewhat similar in form
to the arches found in Yucatan; it consists of two immense granite
stones of immense size, meeting in a point and forming a sharp angle.

[Figure: Stone Arch at Gizeh.]

Of the accompanying plates, No. 2 represents the arches in the walls of
Tiryns, copied from Sir W. Gell's Argolis; No. 3, an arch (called
Cyclopean) at Arpino, in the Neapolitan Territory; No. 4, the most
common form of arch used by the ancient American builders. A striking
resemblance will doubtless be observed, indeed, they may almost be
considered identical; and it may be added, that at Medeenet Haboo,
which forms a part of the ancient Egyptian Thebes, a similar
contrivance was observed by Mr. Catherwood. From this it will appear
that the true principles of the arch were not understood