58 Invention of Efcapemtnii ahfohtely detached, 



the remaining femi-arc k E, winds up the fpring v through the further angle k C E = i oS% 

 and returns through the femi-arc Eo, by the joint action of the balance fpring and the auxi- 

 liary fpring V, both of which ceafe to accelerate? the balance the inftant it has arrived at O. 

 It may be remarked, in this curious efcapement, that the motion of the balance in its 

 femi-vibration from the point of quiefcence is oppofed through an arc of no more than 

 108, but is accelerated in its return through the whole arc of 135**, and that the dif- 

 ference is what maintains the vibrations; and moreover, that the force from the wheel 

 being exerted to wind up each auxiliary fpring during the time it is totally difcngaged from 

 the balance, this laft organ cannot be affedted by its irregularities, except fo far as they 

 may render it more difficult to difengage the rim of the pallet from the tooth. The balance 

 defcribes an arc of about 8** during this dlfengagement. 



From a paffage in a pamphlet of Mr. Mudge, printed in 1763, which I have feen, and is 

 quoted by Count Bruhl *, it is clearly fliewn that that artift had the notion of the principle 

 bf this efcapement in his mind at lead thirty-five years ago. From the fame author's de- 

 , fcription it appears that Mudge had organized his notions in the prefent form before 

 Auguft I77i> and completed his firfl; time-keeper two years afterwards, viz. in 1773. The 

 performance of fuch time-keepers as have been made on this conftrudlion has proved ex- 

 cellent, but not fuperior, as 1 am informed, to fuch as have been made with the efcape- 

 ment No. 4. There are, however, many circumflances in the execution of the workman- 

 ship of engines of this delicate nature, which mud affedl their performance whatever may 

 be their principle. The theory of Mudge's efcapement appears to be more perfeft than 

 that of the other. But whether its fix pivots in the time-meafurer, which require oil and 

 adjuftments for pofition when intended for the pocket, and the care required in fettling 

 the points of quiefcence in the three diftindl: fprings, may render it lefs eafy to be carried 

 into pra£lical efFcwt, will be in a great meafure an obje£l; of opinion, into which I cannot 

 now enter. 



If Mr. Mudge was the firfl who imagined an efcapement abfolutely detached, I think it 

 is to Mr. Alexander Gumming that we are indebted for the firft execution of a like con- 

 trivance of his own. This well-known artift, in the year 1 763, made a clock for the king, ia 

 ■which there was no fridion during the repofe of the movement, and the maintaining 

 power was applied to the inclined faces of a pair of pallctsf ; and fome time previous to 

 J766, he improved the fame fo as to render it as perfeflly detached as, in the nature of 

 things, an efcapement can be. As this has been fo many years in pofleflion of the public, 

 and is, as I think, fimplified in the fketch, fig. 8, — I flwll only fay that it confiits of an an- 

 chor like that of Graham, but having a detent or claw at each end in (lead of pallets, and 

 two feparate pallets prefled (by a lever and weight to each) tov/ards the centre of a wheel 

 like AB, fig. 2 ; that thefe pallets are feverally raifed during the abfence of the pendulum, 

 which difplaces the detent, by virtue of which, when the pendulum becomes joined with 

 either, the maintaining force is conftant and greater in the defcent than in the afcent. It 

 feems reafonable to infer, that Mr. Mudge mull have paid great attention to the efcape- 



• On the inveftigation of aftronomical circles ; (page 3, of regifter) a pamphlet of 3 2 pages oflavo, printed ia 

 London 1794. — 



f Cumming's Elements of Clock and Watch Work, p. 7S. 



ment 



