For anyone interested in medieval or Gothic design: you're cordially invited to surf by for several Gothic geometry lessons online at New York Carver run by yours truly, a professional stone carver. I apprenticed at the Cathedral of St. John the Divine in New York and was one of the few Yanks to sit for London's City & Guilds exam in stone masonry.

In the US, stone masons and carvers rely heavily on E.G. Warland's manual (the British 'mason's Bible') for designing rose windows, trefoils and other tracery examples. However, that book and those like it have been out of print for years.

There is available now a downloadable e-book on the subject that goes into much greater detail, but it's not necessary to purchase it to take advantage of the free lessons online. The idea for the e-book actually was suggested by a California educator, who wanted to peak the interest of his boys in the real-world application of geometry.

Hope this helps.

Joe Chiffriller
New York Carver
Tips & Tricks to Gothic Geometry
Tips & Tricks to Gothic Geometry