"Roofs in the shape of dishes ... have been built ...by the following
procedure. A reinforced concrete ring is first poured on top of a circular
wall (or a series of columns set in a circle) and steel radial cables are
strung from the outer concrete ring to an inner smaller steel ring set about
one-tenth of the span lower than the outer concrete ring and temporarily
supported on a scaffold. A series of prefabricated, pie-shaped concrete
slabs is then set on the radial cables...After that, the radial and circular
joints between the slabs are filled with mortar."

p. 121-122 Art of Construction