of the Life and Works of M. Breguet. 211 



the dial, without producing any change on the motion of the 

 instrument. * We may measure, also, with rigorous exact- 

 ness, the duration of observed effects, which is the object of 

 a great number of physical researches. We ought to add, 

 that a French artist, M. Rieussecq, first employed a process 

 of this kind for civil purposes. M. Breguet changed the cha- 

 racter of the instrument, and has given it a new degree of pre- 

 cision. 



We may mention also a singular instrument formed of a 

 lens, which oscillates continually without any external im- 

 pulse. At the Conservatoire des Arts et Metiers^ there is a 

 clock of this kind, which was made for the Duke of Orleans. 

 The body which oscillates is suspended by a long rod to a 

 single fixed point, and is otherwise entirely insulated. The 

 total mass vibrates without any renewal of the impulse by an 

 external cause. The oscillation of the lens is the effect of the 

 moveable apparatus which it contains. The changes of tem- 

 perature are compensated by the variation in the form of the 

 suspension rod. We may enumerate, also, the valuable clocks 

 possessed by the King of France, the Dauphin, and the sove- 

 reigns of countries where the arts are best appreciated ; — the 

 admirable works which adorn the museum of M. de Somma- 

 riva; those which have been made for the Duke of Cam- 

 bridge, the Duke of Bedford, and other wealthy individuals ; 

 and in short, other objects destined to mark the last progress 

 and superiority of French clock-work. 



The works of M. Breguet have indeed a very high value, 

 and to possess them has become a mark of opulence. But 

 while he has enriched the apartments of royalty with the won- 

 ders of art, he applied himself with the same care to discover 



* The following ingenious inventions ofM. Breguet^ including those 

 above-mentioned, are described in the Edinburgh Encyclopcediu, article 

 Science Amusements in, vol. xvii. p. 576. 



1 . Breguet's Eye-piece Chronometer, for counting fractional parts of a 



second. 



2. Breguet's improvement on Rieussecq's Chronograph. 



3. Breguet's Chronometer, with Double Seconds. 



4. Breguet's Double Sympathetic Chronometer. 



5. Breguet's Sympathetic Clock. — Ed. 



