276 INVENTION or CHRONOMETERS, &;C. 



who gave a fovourable account of it;* and some other trials 

 were after\var,ls made in France and Holland with variois suc- 

 cess, which the author f attributes to the bad managentfint of 

 those who had charge of the nmchines, but which we may 

 venture to ascribe principally to the nature of their construc- 

 tion. Huygcns' timekeeper was maintained by a spring, legu- 

 lated by a pendulum, and the whole was suspended in such a 

 manner as was supposed most proper to procure the indispen- 

 sable stability. 

 Timepieces Timepieces with a pendulum regulator are certainly the rcost 



Jumari'bei'forP'''"^'^^*' ^"^^^ ^^'^>' ^"^^ ^^^^ '" ^ ^^^^ situation; and, for tbat 

 land use: reason, these are the only sort used in astronomical observato- 



ries. But external motion is so contrary to the regularity of 

 their performance, that no sea chronometer has been since at- 

 —those with a tempted to be constructed upon that principle. The balance ' 

 a ance or sea. j.eg^i]j^,-oj. remained, as affording the only method by which the 

 desired uniformity miglit be obtained in portable machines ; 

 . and the great improvement made in that regulator, by the ad- 

 dition of a spiral spring, may be considered as one principal 

 cause of the perfection which has been since attained in them. 

 The first invention of attaching a spring, to give to the balance 

 by its elasticity a power which renders the action of this sort of 

 regulator similar to that of gravity in the pendulum, is un- 

 The balance doubtedly due to Dr. Hooke, though it is not so clear whether 

 tenTeVby "" ^'^ ^^'^^ applied it in the shape of a spiral, as has been so long 

 Robt. Ho®ke. practised since. F. Bertiioud, in his Htstoire de la Mesiire du 

 Temps, (vol. i. pp. 134 to 141), gives a body of extracts frcm 

 several M^orks relative to this subject ; and concludes, that Dr. 

 Hooke only applied- a straight spring to the balance, and that 



Kistorical re- M. Huygens improved upon that idea, and -contrived the spiral 

 marks, &c. on . , . , . „' , , ^ 



the balance sprmg, which IS more favourable to the vibrations of the ba- 



»pring. lance. M. Huygens, indeed, applied in France a balance 



spring, the account of which has been published in the Philo- 

 sophical Transactions for 1675, No. 112; but Dr. Hooke, in 

 the Postscript to his Description of Helios6opes,t asserts that 

 the hint was taken from tha experiments he had made in iC6'4, 



* Philosophical Transactions, 1665, vol. i. p. 13. 

 t Ilorologium Oscillatorium, 1673, p. 17. 

 t Lectioncs Cutlerian;^, 1079. 



