Fine ajustements

Fine ajustements


Before continuing our description of the compteur, which, as we can already see, is a truly exceptional instrument, we would like to mention another way in which the compteur could be adjusted, that further demonstrates (if such proof were needed) the high degree of precision that Louis Moinet was eager to achieve. This is the particularly efficient (and no doubt unprecedented) adjusting mechanism used to reset the thirds hand. 
This lever is shown once more in figure 48, where we can see that it is blocking the escape wheel (see red circle) by making contact with the wheel's locking arm. If, when in this position, the thirds hand is not exactly in line with the small black dot on the dial (as is shown, for example, by the red line in figure 49), then it needs to be moved back to the centre of the black dot, as shown by the black line. Moinet invented a device similar to the chariot used in verge escapements to carry out this delicate operation. The lever is made up of 2 parts: 
1) A base, around which the lever can pivot (as shown by the dotted red rectangle in figure 48 and in more detail in figure 48a). 
2) The lever is attached to the side of this base using a slide-bar. The lever is fixed to the base from the side by a locking screw (1). However, at the back there is another screw with a flange (2), which allows the lever to move forward and back. This allows the user to finely adjust the thirds hand so that it points to the zero on the dial. 
Example: In this example, the hand is slightly to the left of the zero marker (shown by the red line in figure 49). It therefore needs to be moved to the right. The side screw is slightly loosened and, by looking at figure 48, we can surmise that if the screw with the flange is screwed or unscrewed, the lever will move either upwards or downwards respectively. In this instance, the screw with the flange needs to be screwed on. This 'lifts' the lever, causing the escape wheel to turn slightly thus repositioning the hand precisely on the zero marker. 

Jean-Marie Schaller: Memories of the Future

By Constantin StikasPhotographer and journalist
We frequently say that everything in watchmaking was invented in the 18th century and Jean-Marie Schaller arrived to prove this to us, on the first day...

The Inventor of the chronograph