Horologist Question:

One-twelth of a Ligne. A unit of measurement used for (usually) Swiss and French watches. Often used to state the thickness of the watch movement. One Ligne is 0.1879mm or 0.0074 inches. There are 12 douzième to one Ligne, 12 Ligne to one French inch (pouce, French for thumb) and 12 pouce to a French foot (Pied).