of the Life and Works ofM. Breguet. 203 



tain and renew it. That, in short, which was once an obstacle 

 is now an useful auxiliary. 



The name of perpetual watches has been given to those 

 which are always wound up by the motion of the persons who 

 carry them. This invention is an old one, but it continued 

 too imperfect to be used. M. Breguet has given to such watch- 

 es all the precision and stability which they require. In or- 

 der to make them go three days, it is necessary only to shake 

 them a few minutes ; and there are some of them which have 

 preserved their motion regular for ten years without having 

 been opened. • 



We may even construct watches so that they may be wound 

 up by the sole effect of the natural changes in the temperature, 

 or weight of the atmosphere, or by the effect of a current of air. 

 Several instruments of this kind have been made ; but they are 

 not connected with the essential part of the art, the true object 

 of which is to maintain an uniform motion, notwithstanding the 

 external causes which tend to disturb it. 



The most important parts of the interior mechanism of a 

 watch, and which form, if we may so speak, its principal organ, 

 are the escapement and the balance. It is here that the regu- 

 lating power resides, and the least irregularity in its action will 

 occasion a sensible disturbance. But the balance is subject to 

 take very different positions, and its weight does not always act 

 in the same manner. One of the most ingenious inventions of 

 M. Breguet is that for preventing this kind of inequality. He 

 has contrived to give to this part of the mechanism a circular 

 motion, which, in the interval of each minute, nearly renews all 

 possible positions. The errors of eccentricity, the variable ef- 

 fects of friction, all the inequalities which depend on position 

 thus compensate one another, and disappear in the mean re- 

 sult. 



The arts have their principle and their models in nature, and 

 this is particularly true of the science of the civil division of 

 time. The regular motions of the celestial bodies have given 

 us the idea of an uniform duration. According to the ex- 

 pression of the most eloquent of philosophers, the stars are the 

 instruments of time ; but it belongs only to science in its most 

 perfect state to recognize the constancy of nature in the spec- 



