Sundial cannon

A sundial cannon, sundial gun, noon cannon or meridian cannon, also noonday gun is a device consisting of a sundial incorporating a cannon with a fuse that is lit by an overhanging lens, concentrating the rays of the sun, and causing the cannon to fire at noon, when properly oriented along a north–south axis. The cannon sizes ranged from large to small depending on the location of their use. The household variety was used in estates to signal the time for the midday meal. Larger sizes were used in European parks to signal noon.

The cannons were used by European royalty in the 18th century. Cannons of this type are exhibited at the National Maritime Museum in Greenwich. The Hamilton Watch Company has a sundial cannon manufactured by Rousseau of Paris ca. 1650. The Rousseau cannon is mounted on a marble sundial and is made of brass. The Sultan of Morocco also owns one that was manufactured by Baker & Sons of London.

Currently the only sun cannon in regular operation was installed in 1853 in a tower in the park of Adelsnäs Manor in Åtvidaberg, Sweden. Its 6-pounder gun fires daily from May through August (manually lit on cloudy days).