Dial and movement signed. DIM. 20.6 x 18.7 x 6.1 cm. This attractive Art Deco clock has an unusual and very rare movement construction which gives the clock a duration of running of 30 days with a relatively small-size movement. This was the invention of a Geneva maker Philippe Ren Jaccard and the description of the patent is as follows: PATENTED JULY 13, 1943 DRIVING MECHANISM PHILIPPE REN JACCARD, Petit Lancy, Geneva, Switzerland Application April 2, 1941, Serial No. 386,557 In Switzerland April 1, 1940 6 Claims. (Cl. 185-40). This invention relates to driving mechanism of the type including an auxiliary spring for transmitting the driving torque with a constant force to the driven element. Driving mechanisms of this type are used for example in clock movements having a powerful main spring which ensures a long running period, in order to avoid the disadvantageous variation of the driving force of the unwinding spring on the running precision of the movement. Known devices of this kind are of complicated and unreliable construction and can be used only in combination with clock movements of considerable size. It is an object of the present invention to provide a driving mechanism having an auxiliary spring, of the type referred to, which may be used also for small clock movements, for example in combination with pocket watch movements and Chronometer movements, or also for speed indicators of vehicles.