|This article needs additional citations for verification. (December 2008)|
|2.256×10−3 m||2.2558 mm|
|US customary / Imperial units|
|7.401×10−3 ft||88.81×10−3 in|
The ligne (from the French word meaning "line") is a unit of length that was in use prior to the French adoption of the metric system in the late 18th century, and is still used by French and Swiss wristwatch makers to measure the size of a watch movement.
There are 12 lignes to one French inch (pouce). The standardized conversion for a ligne is 2.2558291 mm (1 mm = 0.443296 ligne), and it is abbreviated with the letter L or represented by the triple prime, ‴.
In the 9th century the term ligne came into use among German button makers, where it was used to measure the diameter of buttons. The consensus definition was that a ligne was the measurement of a round wick, folded flat. In this sense it measures 1⁄40 of an inch, but not exactly, for there were several inches in the kingdoms and petty states of Germany at that time. Such a measurement became the American measurement called "line," being one-fortieth of the US-customary inch. Its use was again to measure buttons, and was probably introduced by German immigrants.
The ligne system is in some instances still in use for buttons or snap buttons, where the size number of the button refers to ligne.
The term also continues to find use when referring to ribbon widths of men's hat bands.
- Foire aux questions sur l'horlogerie et les montres, horlogerie-suisse.com, retrieved 2010-06-30. (French)
- Oxford English Dictionary