If you draw a circle from a center found
Inside an arch and just go round
You can make your bricks all march
In step with a Roman arch
If you select more than one
Center you can have some fun
With different sized radii.
Plays a trick upon the eye
An arch with some different centers
Will create like an inventor’s
Idea of a rounded form
And step outside the circular norm.
The effect of vertical mullions
is an architect's ebullience
for fancy windowed mansions
with horizontal transoms.
If you are a really big fan
of giant windows with widest span
be careful and listen as I beseech
you not to weaken and overreach
As you design your giant window
there's a limit how far to go
If your engineer's skill does lapse
Your giant window will collapse.