Plates LXIII and LXIV. Circular Staircases with Domical Ceilings

Plates LXIII and LXIV. — The circular staircase on a large scale is rarely adopted for more than one or two flights, as it is primarily of use in connection with the design of a rotunda which itself is but an incident in a grandiose scheme. The diagrams Nos. I, II and III show circular staircases rising from one or more floors, Sir Christopher Wren’s geometrical staircase in St. Paul’s Cathedral, No. II, being unique as regards the number of steps, daring construction, masterly design of the lower flight and diminished width of the upper flights. No. IV shows short flights adapted at three points in the design of a rotunda, giving access to a circular corridor and subsidiary passages, and at the same time leading to a central flight of steps at the head of the vista. The plan and section given in Nos. V and VI show a variation of the principles illustrated in No. IV. A segmental flight is disposed between the podium of a circular peristyle and continued by a straight flight on the main axis beyond the circular plan. In these examples the student will recognise an extension of some of the circular domed motives which have been discussed in Series I of this book, and an interesting composition which includes curved steps and screens within a circular domed building is reproduced on Plate LIV.

The treatment of the top landing calls for rare skill in the adjustment of peristyles, domical coverings and lantern lights. The use of a dome is readily suggested by the ring of columns in the example from Wardour Castle, illustrated on Plate LXIII, but even over a rectangular plan the domical covering may be relied upon to give excellent results, as may be judged from the other perspective sketch reproduced on the same Plate.