Effefl of Magnettfm on Ttme-pl'cces. 17 



difficulties which the maker has to encounter, thinks himfelf 

 ill ufed, and the latter fuffcrs at the fame time in his repu- 

 tation as an artift; and in his character as a man; and when 

 the watches happen to have heen made for nautical purpofes, 

 or for exportation, the whole community j in fome meafure, 

 become fufferers. 



The intention of the prefent paper is to point Out a defect 

 in the contraction of time-pieces of every defcription in 

 which balances are ufed, and at the fame time a fource of 

 error in their performance, which has been hitherto little 

 if at all fufpectedj but which> where it occurs, completely 

 defeats all the ends intended to be anfwered by the applica- 

 tion of the above-mentioned ingenious contrivances : and 

 that it does occur very frequently, will be made fufficiently 

 obvious by a fimple detail of facts fupported by actual ex- 

 periments. 



That the balances of watches, when manufactured of 

 fteel, as they moftly are, might be in a fmall degree magnetic^ 

 and confequently have fome influence in difturbing their 

 vibrations, has been fufpedled by fome and denied by others : 

 but that a circular bod)-, fuch as a balance is, fhould poffefj 

 polarity 5 that a particular point in it fhould have fo ftrong 

 a tendency to the north, and an oppofite point an equal 

 tendency to the. fouthj as to be fufficient materially to alter 

 the rate of going of the machine when put in different 

 pofitions, ha9 never, I believe, been even fufpecled. If it 

 ' had, the ufe of fteel balances would have been laid afide long 

 ago, particularly where accurate performance was indifpen- 

 fible, as in time-pieces for aftronomical and nautical purpofes. 

 Though I have frequently examined, with great care, watches 

 that did not perform well, even when no defect in their 

 construction or flnifhing was apparent, and fufpected the 

 balance to be magnetic, yet I never could have imagined 

 that this influence, operating as a caufe, could produce fo 

 great an effect as I found upon actual experiment; for I 

 did not expect to find that a balance, even when magnetic, 

 ' Vol. I. C fhould 



