Gothic Geometry
Billings Durham Cathedral
William Radford’s 1909 “Cyclopedia of Construction” contains a progression of Elementary-Beginner tracery arches and constructions https://archive.org/details/framingapractic03johngoog/page/n59/mode/thumb/66
Robert Billings’ 1840 “Architectural illustrations, history and description of Carlisle cathedral” Beginner-Intermediate window tracery designs https://archive.org/details/architecturalill00bill_1/page/n135/mode/2up
Robert Billings’ 1842 “Illustrations of geometric tracery, from the paneling belonging to Carlisle Cathedral” intermediate tracery panellings patterns https://archive.org/details/illustrationsofg00bill/page/n42/mode/2up
Robert Billings’ 1851 “The Power of Form Applied to Geometric Tracery” is a compilation of numerous Advanced tracery constructions https://archive.org/details/powerofformappli00bill_0/page/n30/mode/thumb