5(J VIBRATIONS OF A BALANCE. 



thefe engines would not be advifeable, even if Lewis had 

 been in the right in fuppoiing them to fave water. Thefe 

 rough computations, or rather eftimates, are fufhciently near 

 for data (o look: as thofe upon which we have operated ; and 

 they appear to (hew that the principal, and perhaps the only 

 recommendation of the water engines is, that many of them 

 may be made and applied at a fraall charge, in fituations 

 where water with a proper fall is plentifully to be had. 



XII. 



A Method of rendering the long and jhort Vibrations of a 

 Balance, governed by a Jpiral Spring, precifely equal in 

 Duration. By Mr. Charles Young. In a Letter from 

 the Inventor. 



To Mr. NICHOLSON. 

 SIR, 



Wo explannt'on 1 HAVE lately tried many experiments upon fprings, with 



ha-j be™ given a v j evv f obtain fome knowledge of the caufes which govern 



why the l> ng ° ° 



and fh< t t v;bra- an effect that is very troublefome to all makers of chronome- 



fionsof a ba- ters . name lv, that the vibrations of the balance through Qiort 



Unci are difler- "\ . . . 



Mti arcs, confuting or perhaps ninety degrees, are in iome m- 



ftruments performed in longer) and in others in fhorter times 

 than thofe long arcs, fuch as of four hundred. It is certain 

 that no fatisfaclory reafons have been given, either in 

 England or in France, to (how how this irregularity is pro- 

 duced. 

 A balance fuf- * made a piece of brafs to ferve as a large watch balance, 

 pendid by a and fufpended it by a bit of fpring wire, on which it could 

 /trait wire had v j Dra t e as an ax j s then having turned it four or five times, 



jts bng znn \ >••! 



ihort vibrations I left it to regain its natural pofition*. It performed all its 



equal. 



* This method of fufpenfion has been ufed for philofephical 

 purpofes, by Mr. Mitchell, (fee Prieftley's Optics,) hy Mr. Caven- 

 dilh, (fee Philof. Tranf. and alfo this Journal quarto II. 44-6.) 

 by Mr, Coulomb, in his numerous experiments on Electricity and 

 Magnetifrn} and by Mr. Berthoud, in his Time Piece, No. 24. See 

 his Tjcatife de la Meanire du Temps, p. 50. It does not appear 

 that this fpring has yet heen ufed by itfelf in time pieces. N. 



ofcijlations 



