INVENTION OP CHRONOMETERS, &C. 275 



invention of a spring remontoir, as a new thing ; and Dr. — claimed by 



dook.6 * 

 Hook* on this occasion* asserted, that he had also known that 



way fver since A. 166O; but, as he had never declared it to 



anytody, he could not say that it had been taken from him. 



The principle of the remontoir has since been adopted by J. 



Harrison and some others, but it has never become general ; — and adopted 



and it is supposed that we actually possess more simple means ^ Harrison. 



of ittaining the same advantages. 



The greatest step ever made in the improvement of the re- Great improve- 



gu.ator of timepieces was the application of the pendulum for ^^/"^(,|: j,v the' 



that purpose ; and the merit of the invention cannot be denied application of 



to Huygens, who executed and explained it in the most satis- the pe««?M/ujn .• 



factory manner in his Horolosium Oscillatorium, though cer- —ascribed 



• , , 1 ... 1 • 1 1 • 1 r , chiefly tg Hur- 



tamly he was not the nrst who conceived the idea 01 employ- ggus. 



ing the pendulum to measure time, nor even perhaps the first 

 who thought of attaching it to a clock. The complete practi- 

 cal benefit of the pendulum was not, however, the result of the 

 profound investigations of that great philosopher to procure 



cycloidal vibrations : and its accomphshment is due to the in- Cycloidalri- 



• /-I 1-1 brations. 



vention of the anchor and dead-beat escapement, which, per- Anchor «scape- 



mitting only narrow vibrations, obviated the inconveniences"^^"** 



observed when the pendulum, suspended on a thread with 



cheeks to modify the vibrations, was used with the old recoil 



escapement. Huygens also invented the application of a pen- 



<iulum with conical or circular motion, and the theory and Conical pendn. 



contrivance, used by him for that purpose, do great honour to *"• 



his genius ; but the success did not answer his expectation, 



and it does not appear that any attempt has been since made 



to render those principles useful in practice. 



Huygens constructed a timekeeper for finding the longitude The first time- 



at sea,, which is the first practical attempt of that kind that was b^^Ju ^^q^s'^* 



attended with any degree of success ; though the notion of de- with a pendu- 



termining the longitude by that method was proposed so early "' 



as the beginning of the seventeenth century by Gemma Frisius,t 



and followed by Mctius and others. A timekeeper of the con- 



"jtruction of Huygens was tried by M^jor Holmes in l664, 



* Philosophical Transactions, 1675, No. 118. 



t De Priucipiis Astronomite et Cosmographije, 1530. 



N n 2 who 



