"Obviously, we have here the principle of the arch. Speaking generally, I believe that the Egyptians were acquainted with that principle from the earliest times. They did not make an extensive use of the arch because they knew that it carried within it the seeds of its own death. _Une maille rongée emporte tout l'ouvrage_, and a bad stone in a vault may ruin a whole building. The Egyptians preferred their indestructible stone beams. I often ask myself how much would have been left to us of their tombs and temples if they had used the arch instead."[81] [81] "An arch never sleeps" says the Arab proverb. [Illustration: FIG. 44.--Arch in the necropolis of Abydos; communicated by Mariette.] Mariette adds that the Serapeum contains the oldest known example of a vault of dressed stone, and as it dates from the time of Darius the son of Hystaspes, we suppose that the fine limestone arch at Sakkarah, bearing the cartouche of Psemethek I., which is figured at the head of Sir Gardner Wilkinson's tenth chapter, no longer exists. It was in their brick buildings that the Egyptians chiefly employed arches. Such structures were looked upon as less sacred, less monumental than those in which stone was used, and a process might therefore be admitted which would be excluded from the latter. We shall here give several examples of the Egyptian arch and its principal varieties, and it will not surprise our readers to find that they are all taken from the New Empire. The remains from earlier periods consist almost entirely of tombs, while those left to us by the eighteenth dynasty and its successors are of vast dimensions, such as the great Theban temples, and have annexes comprising buildings erected for a vast variety of purposes. Groined vaults were unknown to the Egyptians, but almost every variety of arch and of plain vault is to be found in the country. The semicircular arch is more frequently met with than any other. That which exists in an old tomb at Abydos has been already figured (Fig. 44), we shall give two more examples, dating from the Sait epoch. The illustration below (Fig. 45), represents the gate in the encircling wall of one of the tombs in the valley of El-Assassif, at Thebes. The wall diminishes gradually in thickness from sixteen feet eight inches at the bottom to nine feet nine inches at the top, both faces being equally inclined. This latter feature is a rare one in Egypt, the slope being as a rule confined to the external face. In order to show it clearly we have interrupted the wall vertically in our illustration, isolating the part in which the arch occurs (Fig. 46), and restoring the summit. The arch itself is formed of nine courses of brick. [Illustration: FIG. 45.--Arch in El-Assassif, present condition; from Lepsius.]