Dialling usually means to make a telephone call by operating its rotary dial.

Etymology

The word, dial, comes comes from the Latin dialis = "daily", because a sundial throws a shadow related to the time of day. It was also used to describe the gear in a medieval clock which turned once per day.

The word dialling originally referred to the creation of the mathematics required to create a sundial face to tell time based on the position of the sun. Those skilled in the art were referred to as dialists or gnomonists; taken from the word gnomon (a device using a shadow as an indicator).

The mathematician William Oughtred published a book, Easy Method of Mathematical Dialling, around 1600. Samuel Walker (1716-1782) was a Yorkshire mathematician and diallist ]. In his later years, Thomas Jefferson was known to practice dialling as a mental exercise. Professor of astronomy at Gresham College (London, UK), Samual Foster (d. 1652), developed reflex dialling, which describes a device of his own invention: a sundial capable of reflecting a spot of light onto the ceiling of a room.

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