274 INVENTION or CHRONOMITERS, &C. 



now for the first time been produced, capable of determining 



the longitude at sea. 

 General des- The machines which, for centuries, have been commonly 



cMne's for mea- "^^^ *° measure time, consist of a movement, or train of wheels, 

 suringtime. drawn by a weight or spring, and a regulator, the object of 



which is to keep the motion of the train within the required 

 The train and degree of uniformity. A continual rotatory motion, which 

 partr^"^^^'"° constantly tends to accelerate, is thus corrected by means of 



an alternate motion ; while the power which carries round the 



movement restores, also, to the regulator the action lost by 



The escape- friction and other causes. The mechanism, by which the two 



jnent is the • • i ^ ^ ,t • ,, , , 



great character Principal parts act on one another, is called the escapement; 



of modern and this most admirable contrivance may be reckoned the dis- 

 ^ '^^ ^' tinguishing characteristic of the modern art of timepiece ma- 



king. It is not the object of the present inquiry to trace the 

 history of the successive alterations and improvements made in 

 the construction of clocks and watches upon that principle j 

 but briefly to mention such inventions as have been proposed 

 from the middle of the seventeenth century, and have had a 

 direct influence on the progress of chronometry. 

 Great improve- A very ingenious invention to improve the movement, or 

 Ty^!/^etmolt;^^^^ P^^^ "^^ ^he timepiece which is corrected by the regulator, 

 is the remontolr. The action of the movement on the regula- 

 tor suffers continual alterations, by the inequalities which pro- 

 ceed from the nature of the weight or spring, and by thostt 

 which occur in the friction of the pivots and teeth of the 

 wheels. In order to prevent those alterations from affecting 

 the regularity of the going of the machine, the usual weight or 

 —which is a spring has been employed, only to wind up, at very short inter- 

 wincUng up^ ^""^ ^^^^ °^ ^^'""'^' ^ secondary power, which may thus be supposed 

 very frequently to be uniform, and is the one which acts immediately on the 

 wWcra'^^tson I'^g^^ator, by means of the escapement. This contrivance 

 the regulator : seems to have been executed about 16OO ;* but Christian 

 thus more" imi- ^uygens is the first f to whom we are indebted for an expla- 

 form. nation of this kind of mechanism, with a weight ; and he 



-Ixplahicd by P^bably conceived that idea without any previous hints from 



Huygens.also others. Leibnitz, however, a little afterwards J published the 



by Leibnitz : 



* Histoire do la Mesure du Temps, par F. Berthoud, vol. ii, p. 41. 

 t Horologium Oscillatorium, 1673, p. 18. 

 t Philosophical Transactions, 1075, No. 113. 



