Crown glass was the old-fashioned method a making glass by spinning a small globe of blown molten glass on the end of a hollow iron puntil or punty stick, into a large, thin, circular disk, usually just over five feet in diameter. Sheets were cut from this disc leaving a pane containing the centre where the puntil stick was attached. These panes were considered inferior and therefore cheaper and were used in applications such as the glazing of stable and works areas, and in prisons (see below).
 
The term bull's eye was given by glass-makers to the puntil mark prior to the early 19th century. Fake bull's eyes are now made for decorative use, such as in theme pubs.
 
In 1809, the fourth report for the commissioners for roads and bridges in the Highlands of Scotland stated (with reference to women's prisons) that, 'in all apartments in which work is to be performed the glazing of windows should not be omitted and the sashes should be so constructed as to be capable of being fixed to any degree of aperture and mould likewise be made of bull's eye glass'. Published by the House of Commons in 1809. This would seem to be the earliest written reference to the term 'bull's eye glass' used to describe a small pane of crown glass which shows the puntil mark.
 
Salvo has also heard of this glass being called 'bull's nose' glass and 'bubble' glass.