101. Section of Tomb near the Pyramids of Gizeh.
In the age of Psammeticus we have several stone arches in the neighbourhood of the pyramids; one, in a tomb at Sakkara, has been frequently drawn; but one of the most instructive is that in a tomb discovered by Colonel Campbell (Woodcut No. [101]), showing a very primitive form of an arch composed of 3 stones only, and above which is another arch of regular construction of 4 courses. In his researches at Nimroud, Layard discovered vaulted drains and chambers below the north-west and south-east edifices, which were consequently as old as the 8th or 9th century before our era, and contemporary with those in the pyramids of Meroë. They were of both circular and pointed forms, and built apparently with great care and attention to the principles of the arch (Woodcut No. [102]).
102. Vaulted Drain beneath the South-East Palace at Nimroud.
The great discovery of this class is that of the city gates at Khorsabad, which, as mentioned at p. [181], were spanned by arches of semicircular form, so perfect both in construction and in the mode in which they were ornamented, as to prove that in the time of Sargon the arch was a usual and well-understood building expedient, and one consequently which we may fairly assume to have been long in use.
103. Arch at Dêr-el-Bahree. (Lepsius.)
On the other hand, we have in the temple at Dêr-el-Bahree in Thebes, built by Thothmes III., a curious example of the retention of the old form, when at first sight it would appear as though the true arch would have been a more correct expedient. In this example, the lower arch is composed of stones bracketing forward horizontally, though the form of the arch is semicircular; and above this is a discharging arch of two stones used as in the Pyramids. The upper arch is so arranged as to relieve the crown of the lower—which is its weakest part—of all weight, and at the same time to throw the whole pressure on the outer ends of the arch stones, exactly where it is wanted. The whole thus becomes constructively perfect, though it is a more expensive way of attaining the end desired than by an arch.
The truth seems to be, the Egyptians had not at this age invented voussoirs deeper in the direction of the radii of the arch than in that of its perimeter; and the arch with them was consequently not generally an appropriate mode of roofing. It was the Romans with their tiles who first really understood the true employment of the arch.