Plate XXI. Semi-circular or Exedra Forms

Plate XXI. — Another type approaching the “D” in principle is to be found amongst the works of antiquity and of the Renaissance, the system being akin to the more complex form, but resembling the simple exedra without enclosing screen. Nos. I, II and III show a semi-circular plan which can be carried out with a half dome and pediment or segmental parapet, while No. III includes an Order and a pediment, as used by Sir Christopher Wren. Fig. IV is frankly of the arched type with supporting wings and half pediments sympathetic to the half dome, which is coffered. Fig. V is based upon the Palladian motive. Fig. VI shows a large exedra with pylons on either side against which supporting colonnades terminate: a pleasing variation from the ordinary arrangement of coffering is shown in the semi-dome.

Further examples of this type of plan with concentric peristyles are given on Plates XCIX and C, where they appear as grottoes: see also Fig. 5.