4'28 TIME KEEPliRS. 



know from experience what would be the confequence, ancf 

 have been condemned, beraufe, when I have feen fucJ^ 

 watches I fkid I faw enough to declare that it would not give 

 very accurate perforniaiice. 

 S'aTce"f"fi?'' Balance fpring. To find out the iiivifible properties of this 

 aance pnng. apparent Timple part of the machine, has given much more 

 trouble than all the reft. I defpaired of bringing timekeeper^ 

 to the Rale I have done, and unlefs thofe hidden properties 

 are known to timekeeper makers, however well they may 

 execute all other parts (hey will find their moil fanguine ex- 

 pectations fruftrafed. I have feen watchmakers boaft of their 

 timekeepers going well for a month or two, and from the 

 knowledge I had pf the efFecls produced by the balance 

 fpring, I have Ipld them that a month or two more would de- 

 firoy their hopes. The cylindrical fpring being in all it§ 

 turns of equal diftance frpm the centre, in courfe every turri 

 will be of equal ftrenglh, and called ifochronal, and be- 

 lieved that all vibrations whether long pr Qiort would be per- 

 formed in the fame time ; but this is not true, for if a man is 

 to go four miles in the fame time as he has gone one mile, hq 

 cannot do it with the fame power; np, he muft have impel- 

 ling force to quicken his motion, or he will be four times as 

 Jt Is made ta- long in doing it. Therefore inftead of the fpring being equal 

 ?"'"?• in all its parts, it muft be made to increafe in thicknefs to the 



outer end, in fuch proportion ^s will paufe the balance when' 

 thrown fp a greater diftance to return fo much (he quicker to; 

 make thera equal; by long perfeverance I found how toi 

 ?nake fuch fprings, and then I thought I had got all I wiflied 

 for. But cruel difappoinfment nearly broke my heart, for I 

 found I had yet another difficulty to break down, as my 

 watches with fuch perfed fpring s were continually lofing on 

 their rates. What farther to do I knew not, and I own I 

 was nearly if not quite mad. But obftinate in the caufe and 

 refolving not to give it up but with life, perfeverance came 

 once more tp my aid— and with flill more unremitting ftudy, 

 which nearly finilhed me, before I applied the following re- 

 tpedy for the before mentioned eyil, 1 found, in the courfe of 

 Spnngs are fub- reafoning on bodies, that watch fprings relax and tire like th<j 

 iS o^fbjir" ''"'"^" ^"'"^^ '^'''^" kept conflantly in motion, and this may 

 which is regain- be proved by the Ibllowing experiment: let a watch that has 

 M by reft. been going a few months go down, let it be down for a week 



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