Note 1 — ELEMENTS OF ARCHITECTURAL DESIGN.1
Reading edition
Delivered before the Society of Arts, London, December 13, 1887. From the Journal of the Society.
[2]
A groin is the edge line formed by the meeting and intersection of any two arched surfaces. When this edge line is covered and emphasized by a band of moulded stones forming an arch, as it were, on this edge, this is called a groin rib.
[3]
The "D" seems to have been accidentally omitted in this diagram; it is of course the fourth angle of the plan.
[4]
This was illustrated by diagrams on the wall at the delivery of the lecture.