Page:A History of Art in Ancient Egypt Vol 1.djvu/197

Rh Egyptian vaults may be divided into two great categories, according; to the method of their construction.

Fig. 74. — Element of an off-set arch.

I. Off-set vaults. These vaults are composed of courses off-set one from another, and with their faces hollowed to the segment of a circle. (Fig. 74,)

If the face of those stones which, in the form of inverted steps, are turned to the void which has to be

Fig. 75. — Arrangement of the courses in an off-set arch. covered, be cut into the line of a continuous curve, the superficial appearance of a segmental arch or barrel vault will be obtained ; but this appearance will be no more than superficial, the vault will be in fact a false one, because, in such a con- struction, all the stones which enframe the void and offer to the eye the form.

Fig. 76. — Off-set semicircular arch.

of a vault, are really laid horizontally one upon another, and