The "line": a (not quite) forgotten unit

Though metric (SI) units are generally used when describing a movement, the traditional "line" (sometimes also called "Paris line") is still in use. Piguet, e.g., builds a caliber called 9''' which indicates its size (20.3 mm).

The "line," derived from the old "Pied du Roi," the French "foot," measures exactly 2.2558 mm (1 French foot ['] = 12 French inch [''] at 12 lines ['''] each). 2.26 is a good approximation and easier to use in calculations.
The symbol is a kind of triple apostrophe and not found in any "normal" character set; it can be indicated, as I did here, by writing three apostrophes: '''. Watch journals and books, however, usually use the correct symbol.

Convert lines to mm and vice versa:

(Works with Netscape 4.0 and above, no guarantee for other browsers or older versions)

Copyright © 1996-2002 and responsible for contents: Christoph Ozdoba.
First version 1996; last edited: March 2, 2002.

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