m 



—and oiTcjTit 

 tlierefore to 

 give equal 

 times in all 

 arcs. 



Method of 

 trial. 



AdjustrtiPnt by 

 givinij tVie 

 spriiisj its due 

 lengtih. 



— or by taper- 

 iig. 



T-IMEKEErtR^. 



larity must from tliat cause take place. If the large arc^ are 

 performed in longer time than the small ones, the timekeeper 

 will accelerate, or go faster and faster ; and if the small arcs 

 are performed in longer time than the large ones, it wiE 

 retard, or go slower and slower. To adjust the long and. 

 short arcs, let the timekeeper when clean, and the balance 

 vibrating to its greatest extent, go for a few hours, and then 

 without stopping it, by means of the click and ratchet above, 

 the barrel cap, and a key applied to 10 the barrel arbor 

 square, lei the main spring down a turn or two, till the arc of 

 vibration decreases from 230 to 230 degrees or thereabout. 

 Then let it go for the same time as before, and if it goes, 

 slower with the long arcs than with the short ones, which is 

 generally the case, shorten the springs by drawing it througk 

 the lips of the stud S. Then try it again in the same man- 

 ner, and so on till they are performed in equal times.. 



If on the contrary the short arcs should be performed 

 in longer time than the long ones, or the long arcs be per- 

 f>* med in less time than the short ones, which amounts 

 tu [he same thing, the spring must be let out, or lengthened 

 at the stud 5, and so on repeatedly, until they correspond. 

 If after letting out the spring several times, there should be. 

 no more to spare, a longer spring must be made. The length 

 of spring in the timekeeper before us is about 18 inches. 



If the spring is made of hard rolled wire, and the construc- 

 tion should be such as not to leave room for a spring of the 

 usual length, and one much shorter than ordinary sliould 

 be required, it will be very liable to be overstrained, if of 

 rolled wire, and if hardened'and tempered, or of gold, to 

 break. It wdll however be a good deal relieved and assisted 

 by tapering, the tapered end being pinned into the balance 

 stud j>i. 



Of the Balance, anil tJ/e Mode of mallng ii io keep ihe same 

 Time in different Degrees of Temperature ^ or of adjusting it 

 for the Effects of Heat and Cold. 



The balance 

 has arms of 



Pig. 1 . PI. III.. The balance is screwed upon a collet fixed o» 



, ^ , the end of its ax's fit has two radii or arms and] at the extre- 

 brass and steel _ _ •- / ^ 



Jaiiiiiiac, loaded mitics of these arms are two shoulders cc, against which t/ 

 at the Old. j-^y-Q screv.'s are fixed the expansion or compensation r e.- :. 



