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XXXT. yl mw and most accurafe Method of Banht/ig /he 

 Balance of a Time-keeper. Btj JMr. \V. ILvrdv, oJ' 

 Islington *. 



rr\ ^^^» 



X HIS letter is accompanied with a drawing, a description, 

 and a model, of a, more perfect mode of banking the balance 

 of a time-keeper, than any that has yet appeared ; and its 

 application to a time-keeper is a matter of such real im- 

 portance, that the most accurate, without this most ncees- 

 s^ary appendage, is liable to such derangement, that from 

 the most trivial cause it is in one moment rendered useless. 



To preserve the good qualities of the time-keeper, on 

 which often the strength, the wealth, the grandeur, and 

 safety of tiiis great empire depend, I deem it necessary that 

 my invention should be laid before the Society of Arts, ^s 

 the means of its being more generally known ; and I hope 

 that I show proper respect to the society, when I assure you 

 that I do not offer any crude idea, neither could I think of 

 giving you any trouble until I had fully verified the utility 

 of my contrivance by several years' trial. As I can produce 

 the testimony of some of the most eminent watchmakers 

 in favour of my invention, I look forward with some degree 

 of confidence, in expectation of obtaining the approbation 

 of the society. 



It was at first imagined that a banking to a watch with 

 a free escapement was quite unnecessary, as the lim.its of 

 banking were so great as to admit of almost twice 360,' or 

 720 degrees ; but (m trial the balance was frc<juently foiuul 

 to exceed this quantity, and that a very slight motion gi\cn 

 to the tim.e-keepcr (particularly when the axis of the balance 

 became the axis of that motion) was sufficient to alter tlie 

 strength and figure of the pendulum s)-)ring, and position of 

 the pieces in respect of the balance wheel, so as to change 

 the rate of the time-keeper; and, what was worse, require 

 !i new adjustment of the balance, to accommodate i;self to 

 the changes made in the spring, and other parts connected 

 with it. Hence it became necessary that some means shhuld 

 be used to stop the balance at certain limits beyond its na- 

 tural arch of vibration; and various attempts have been made 

 to efl'ect it. One way is, by a moveal)le piece on the axis 

 of the balance, which banks against a pin, ycl so as to suHer 



• From T.misaitioii! of ihr Sii:iflv of Arts, &c. for 1^:04, — A lioimty of 

 tliir:y guiijtas was votetl 10 Mr. llanly by ilic Society tor tlus coniiiuini- 

 cation. 



