If we are to take it as established that the vault or arch was among the primitive methods of Egyptian construction, we have no reason to believe that off-set arches were older, in Egypt at least, than true arches. We have described this form of arch elsewhere, and explained the contrivance by which the superficial appearance of a vault was obtained.[86] The process could obviously only be carried out in stone. We shall here content ourselves with giving two examples of its employment.
Fig. 49.—Elliptical vault; Thebes.
Fig. 50.—Foundations with inverted segmental arches; compiled from Prisse.
The first dates from the eighteenth dynasty, and occurs in the temple of Dayr-el-Bahari.[87] Our Fig. [51] gives a transverse section of a passage leading to one of the chambers cut in the rock. Fig. [52] offers a view in perspective of the same passage and of the discharging chamber which really bears the thrust of the weight above.
Fig. 51.—Transverse section of a corridor at Dayr-el-Bahari; from Lepsius, i. pl. 87.
Fig. 52.—Section in perspective through the same corridor; composed from the elevation of Lepsius.