Dialling

Dialling, ( dialing in US English), is the action of initiating a telephone call by operating the rotary dial or the telephone keypad of a telephone.

Etymology

The word dial comes from the Latin dialis = "daily", and comes from the fact that 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 determine solar time based on the position of the sun. Those skilled in the art were referred to as dialists or gnomonists, the latter derived from the word gnomon, which was a device that used 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), Samuel 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.