300 i:nvektion of chronometers, &c. 



and others known tb accelerate instead of retarding, during a considerable 

 steady"^ time ; and there are some which have gone for years without 



any material alteration in their rates ; a fact which strongly 

 militates against the rule proposed, as an unfailing and univer- 

 sal method. What would have been the effect of introducing 

 into those timekeepers the invariable excess of five or six seconds 

 Mr. Earnshaw's of the narrow above the wide vibrations, which, like a quack 

 Teuieay IS like medicine, is to cure, without distinction of symptoms or sub- 

 of the aine jects, all the disorders proceeding from the cause of relaxation. 

 !^t-"/",f'^'^_!|" The proposed remedy appears- liable to the objection which 

 the iie.Rhy s naturally occurs on the shghtcst consideration of any compensa- 

 te as les.o • tion intended far circumstances whicLare contingent, and effects 

 which cannot be anticipated. It is at first a source of irregu- 

 larity, v.'hile there is no certainty of its proving an effectual cor- 

 rection of the supposed future changes. And again, even if the 

 relaxation of the springs could be remedied by the shape, or 

 any other essential requisite of the spring itself, it would still be 

 It iacludes the hazardous to adopt a specific variation in that organ, on account 

 consideratoas ^- elltects which might afterwards result from the different 

 oil or di- 1 in thickness of the oil or accumulation of dirt ; two circumstances 

 the macraae; .whieh are too variable and uncertain to appear susceptible of 



v/htch are un- ^^ ^ 



certain. being counteracted by any regular process. Our arguments, 



however, ought to be allov/ed no other force than what can be 

 derived from a clear general viev/ of the subject ; and we will 



Mr. Earnshaw admit, that, if Mr. Earnshaw should be able to produce a series 



ought to exhi- of conclusive experiments in support of the accuracy of his 

 bit facts and . . . ^ . , ^ . , . , ^ T , ■ 



deductions ; so suggestions, with certain rules for practice derived from tiiem, his 



as to aive a remedy for the relaxation of springs would then deserve to be 

 practical rule, , r 



reckoned a valuable addition to the art of making timepieces. 



—and till he In the mean time, the makers will do right to follow that 



does, his reme- niethod which is at present in general use among them, and 

 dy IS not advis- . ,• , , ,- • 



able. continue their endeavours to accomplish the perfection of chro- 



nometers by the, principle of isochronal vibrations. 

 The isoohron- Among the great advantages resulting from the isochronism 

 ism of the of the balance spring, is the facil^jty which it affords to procure 



the advantage wide vibrations, and increase the power of the regulator. The 

 ofwidevibra- irregularity proceeding from the springs, having their wide and 

 narrow vibrations of different durations, was for along time so 

 great an obstacle to that practical improvement, that even the 

 genius of Daniel Bernouilli, to whom we are indebted for very 



deep 



