Egyptian vaults may be divided into two great categories, according; to the method of their construction..jpg)
Fig. 74.—Element of an off-set arch.
1. 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.jpg)
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 construction, all the stones which enframe the void and offer to the eye the form
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Fig. 76.—Off-set semicircular arch.
of a vault, are really laid horizontally one upon another, and
