Arcades
Arcades, as already suggested, may be composed of a series of arches, supported on pilasters which flank the columns. The backs of the piers thus formed may be treated with pilasters, which can be repeated on the opposite wall, with the architrave frieze and cornice above.
There are several alternative treatments for the ceilings of arcades. They may be flat and panelled by beams carried across in a line with the pilasters and with a cornice moulding carried round the sides of the beams.
No. 174. Doric Arcading.
The interior can also be vaulted by means of archivolts springing from the line of the imposts. The archivolts should be supported by pilasters at the back of the piers and on the opposite wall, and a cornice may be carried round between the vaults. Cross vaulting also may be employed, and in this case the entablature is no longer necessary.
The proportions already given determine the width of piers when an order is used, but when an order is not used some further general rules for proportions are necessary.
The height of the opening formed by arches, which may spring from piers—with or without an impost—should be about twice the width. The supporting piers should not be less than a third or more than two-thirds the width of the aperture. In any form of arcading, piers must be employed at the angles, and these should be wider than the intermediate ones by a half, a third, or a fourth.
No. 175. Doric Arch, with pedestal.