A rose by any other name

The 1st Presbyterian Church in Brockville, Ontario was completed in 1879, and is known for having the tallest steeple in the Thousand Islands. What I didn’t know until recently, is that the church features a very unusual window.

I’ve walked past the rose window on William Street many times, but it was only after I took this shot and did some research that I discovered how special it is.

Rose (or wheel) windows have been around for a long time, and while their styles change with the ages, and some are more complicated than others, they are all designed using basic geometry.

There’s an excellent description of how to draw the basic shapes here, and a tutorial on how to draw the rose window at Chartres, France here.

What makes Brockville’s window special is that is has seven spokes (heptagram or septagram). In a survey of 522 medieval rose windows, the authors note that:

The wide variety of divisions of the rose windows is remarkable. The number twelve (27%) seems to be the most common, followed by eight (21%), six (16%), sixteen (9 %) and four (8%). The list also includes odd numbers like seven, nine, eleven and thirteen, which cannot be designed with the compass and straightedge.

I did find a few examples of windows with seven spokes:

Church of Our Lady of the Assumption in Caussade, France

Truro Cathedral, Truro, England

Cathedral Church of Saint John the Divine, New York City, USA

I also found a solution, but it’s not for the faint-hearted, and it’s only a starting point to the window’s design (see here).

The church was designed by James P. Johnston of Ogdensburg, NY, but I can’t find any information about the window. Can anyone help?