A sundial cannon, sundial gun, noon cannon or meridian cannon, also noonday gun is a device consisting of a

sundial A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a f ...

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 The National Maritime Museum (NMM) is a maritime museum in Greenwich, London. It is part of Royal Museums Greenwich, a network of museums in the Maritime Greenwich World Heritage Site. Like other publicly funded national museums in the Unite ...

Greenwich Greenwich ( , ,) is a town in south-east London, England, within the ceremonial county of Greater London. It is situated east-southeast of Charing Cross. Greenwich is notable for its maritime history and for giving its name to the Greenwich ...

. The

Hamilton Watch Company The Hamilton Watch Company is a Swiss manufacturer of wristwatches based in Bienne, Switzerland. Founded in 1892 as an American firm, the Hamilton Watch Company ended American manufacture in 1969. Through a series of mergers and acquisitions, th ...

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 This is the list of rulers of Morocco, since the establishment of the state in 789. The common and formal titles of these rulers has varied, depending on the time period. Since 1957, the designation King has been used. The present King of Moroc ...

also owns one that was manufactured by Baker & Sons of London.

History

The earliest sundial cannons were used in Europe in the 1600s. They were also used in European parks during the 18th and early 19th centuries. The cannon-lens combination was mounted on a sundial. Sundial guns were also used in ships to mark noon. Miniaturized toy versions of the guns were sold in 1979 as unassembled kits by Dixie Gun Works.

Operation

Cannon Sundial by Victor Chevalier, Paris cropped

The gun and the linear ignition groove of the fuse were aligned on a north–south axis, parallel to the one of the sundial, while the lens concentrated the sun rays on the fuse when the sun was directly above. Subsequently, the burning fuse ignited the powder placed in the barrel of the cannon. The lens was mounted on an adjustable frame, which enabled its position to be changed depending on the season. During winter, in December for example, for the small brass cannon manufactured by Rousseau of Paris, the lens had to be lowered by four inches, compared to its position in June as the position of the sun in the sky is lower in winter than during the summer. In naval operations, the gun had to be mounted on a rotating base because its orientation had to be in the north–south direction. The directional axis of the gun was determined using the ship's compass. In such operation, the gun was frequently referred to as the "noonday gun" because it fired at noon. This practice became obsolete when the ship chronometer was invented. The use of the sundial cannon was subsequently confined to substandard ships.

Benjamin Franklin

Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading int ...

wrote the following review about the cannons in ''

Poor Richard's Almanack ''Poor Richard's Almanack'' (sometimes ''Almanac'') was a yearly almanac published by Benjamin Franklin, who adopted the pseudonym of "Poor Richard" or "Richard Saunders" for this purpose. The publication appeared continually from 1732 to 1758. ...

'':

''Popular Mechanics''

In a section of the July 1911 issue of ''

Popular Mechanics ''Popular Mechanics'' (sometimes PM or PopMech) is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do-it-yourself, and technology topics. Military topics, aviation and transportation o ...

'' titled "Women 'Insurgents' in the Farming Business" the writer comments regarding the picture to the right:

In literature

A sundial gun is mentioned in ''

Ellery Queen's Mystery Magazine ''Ellery Queen's Mystery Magazine'' is a bi-monthly American digest size fiction magazine specializing in crime fiction, particularly detective fiction, and mystery fiction. Launched in fall 1941 by Mercury Press, ''EQMM'' is named after the fict ...

''.

References