Glossary · S
Semidome
Also called half-dome, conch, semidomes
Half a dome, covering a semicircular space such as an apse or an exedra. At Hagia Sophia two great semidomes extend the central dome to east and west.
Rules that use the word
Semidomes lengthen the dome. To turn a domed square into a long church, open two of its great arches into semidomes of the same radius, and open the semidomes in turn into smaller exedrae, so that the space expands by stages from the central dome.
Buttress the dome where the semidomes cannot. Where no semidome takes the thrust of the dome, on the north and south, carry it across the aisles to massive buttress piers that rise above the roofs, and fill the great arches with thin walls pierced by windows.
One dome, extended by semidomes. Cover the prayer hall with a single central dome on four piers and extend the unified space by semidomes on two or all four sides, with smaller half-domes (exedrae) in their corners.
The dome on eight piers. To make the domed space as nearly one room as possible, set the dome on eight piers inscribed in a square, and fill the four corners with semidomes on the diagonals.
The cascade of domes. Let the exterior show the structure: pile semidomes, exedrae, corner domes and weight towers round the central dome so that the masses rise in steps to the crown.
Apses in echelon. Multiply altars at the east end by opening apses off the transept arms and the choir, stepped back from the main apse in echelon, each with its own small semidome and roof.
Where it appears in the book
In the chapters Domes, Byzantium and the Early Church, The Islamic World.
Nearby in the glossary
Scroll · Segmental pediment · Seked · Semicircular arch · Şerefe · Serliana · Setback · Sexpartite vault