Geometrical Tracery

Basic Elements of a Gothic Window

Vertical lines of stonework within a window, are called mullions. These divide the window into compartments called lights. So, for example, three mullions will produce a 4-light window.

Stone tracery fills the upper part of the window. As well as providing the main decorative features, the mullions and tracery divide the window into smaller units to carry the leaded panels of glass.

The name geometrical is an appropriate description for this early type of tracery because all the constructions of the window patterns are achieved using only a pair of compasses. Hence all the outline shapes in the tracery consist of circles or parts (arcs) of circles.

To introduce some decoration into a plain circular opening, foil patterns are inserted. These resemble leaves or petals and are created by joining several part-circles together.


In larger windows cinquefoil, sexfoil, or octofoil patterns, with 5, 6 or 8 leaves respectively, may be found.