Details
The mechanical watch movement caliber 691 of the Fabrique d’Horlogerie de Fontainemelon bases on the common FHF caliber 69 and added a center second hand to it. Since the available space is very low on these form watch movements, the FHF had to use an extraordinary solution: The fourth wheel indirectly drives a wheel on the top of the main plate, which itselfs drives the center second pinion. Watch movement dimensions 6.75 x 8 Ligne = 15.3 x 17.8mm, hight 4.2mm, 17 jewels, f = 21600 A/h, power reserve 48h.