SIGNED EBERHARD & CO., PRE-EXTRA FORT MODEL, MOVEMENT NO. 9154. CASE NO. 199'782, CIRCA 1940

Highly rare and sought-after by collectors, the present monopusher chronograph features a very attractive and oversized 39 millimeter 18k gold case and a silvered dial with Breguet numerals. The dial is complex yet perfectly proportioned, with an outer telemeter scale used for measuring distances based on a visible and audible event, such as during a thunderstorm. The divisions on the scale are based on the speed of sound in air (340 meters per second). In the center is a spiral tachymeter scale for measuring speed over distance. Subsidiary dials for the 30-minute register at 3 o’clock and seconds at 9 o’clock provide visual symmetry.

A particularly fascinating feature of this model of Eberhard chronograph is the patented ‘split-time’ mechanism, patented in 1935. At first glance, the watch has the appearance of a typical two-button chronograph. However, it is, in fact, a ‘monopoussoir’ or single-button chronograph. The pusher at 2 o’clock starts, stops, and resets the chronograph, while the pusher at 4 o’clock stops and then locks the chronograph hand by sliding it up towards the crown. Thus, the measurement recorded by the chronograph is preserved until it is recorded by the user and the lock is released.

Eberhard & Co. was founded by Georges Eberhard in La Chaux-de-Fonds, Switzerland in 1887. With the launch of its first chronograph wristwatch in 1919 the firm was quickly recognized as one of the most prominent manufacturers of chronographs in Switzerland.