fiXPERIMENTS ON CHRONOMETERS. 5'5 



aUeration, the former efFe61s totally ceafed; w order to malce It fucceeded.— 



tiie intermediate wheel (which was loofe) fhift one tooth at St^ng detent to 



^ ' ihift the wheel 



every vibration, I made the detent which locked itflrong, and 



inferted a long jewel into it, having an inclined plane that filled 



the fpace between each two teeth that always kept the wheel 



in a certain pofition, the confequence of applying the Itrong 



detent was, that the point of the paffing fpring (or in other 



words the unlocking part) wore very faft, and occafioneJ a — produced wear 



very confiderable retardation of rate, which continued with- '" \^^ paffing 



... 'pringj , 



out intermiflion until the watch flopped from the point of the 



paffing fpring wearing fo much, that the balance could not 

 unlock it. I mufl oblerve, that the arcs of the balance were 



in this, cafe not perceptibly altered, and the retardation not andretarda- 



nearly fo great as the acceleration in the former. I afterwards, tiou. 

 by another contrivance, which it would be difficult to explain, 

 remedied the evil attendant upon a ftrong detent, and produced 

 an efcaperaent perfedly to my wirties, that had no propenfity Remedy, 

 either to accelerate or retard its rate. 



It is clear to me, that friftifin or wearing will, in fome cafes, The fimple de- 

 make a machine accelerate, and in others retard its rate of^^'^ ,|^' 



' ment would per- 



going, therefore I prefume if we could hit upon fome method form well for 



of prefervinsT the ratios of the detached 'fcapement perma- '?"6 Pf "^J"^^ , 

 , . . , ,. ^ 1 I -I- > 1 time if prefervei 



ncnt, by giving the dirterent partsa durability, they have not from wear. 



hitherto polfefled, we might produce machines of this fiinple 

 conflru6tion that fhould retain an equal rate of going for long 

 periods of time, and not look to chance for their fuccefs; if 

 the anions of the 'fcapement were unalterable (which I ima- 

 gine might be made by jewelling) we fhould then have only 

 the influence of the oil to oppofe our fuccefs, which by becom- 

 ing glutinous, will, I think occafion, if any change, a relar- 

 dation of rate, yet if it be good, the effect, I fuppofe, will 

 not be very great in a moderate length of time. 



Having been on (he coaft of Coromandel and Ceylon, and Cocoa nut oil 



other parts of the Eaft Indies, fora feries of eight years, I had =;5^'>'r'"^^",''ed 



' _ _ ' _ o -' ' ior time pieces. 



there an opportunity of trying an oil to watches, which artifls 



here are unacquainted with; being in camp in the My fore 



country, in the years 1791 and 2, for a period of about 



eighteen months, I could fcarcely procure a drop of olive oil 



th.at was not rancid ; I therefore fubftituted in room of it what 



is there called cocoa nut oil, which retains its fluidity to the 



laft. I ptJver knew an infiance of its becoming glutinous, nor 



does 



