Detached Efcapements^ em 



mcnt of Cumnung during his labours for organizing his own, which he did about five 

 years afterwards. 



Fig. 8. is the {ketch of an adaptation of Mudge's efcapement to a clock. LM is part of 

 the periphery of the wheel. GA, GB, are two arms feparately moveable on the fame 

 axis, and terminating in the pallets A, B. Thefe pallets have inclined faces, with a claw 

 or detent at the lower part of each. GO, lO are tails proceeding from each pallet-piece 

 refpecSively, and the dark fpot at N reprefents a pin proceeding from the pendulum rod, 

 and capable of moving either of the tails according to the courfe of the vibration. The 

 dotted circles u and v reprefent weights which are fluck upon two pins, and may be 

 changed for others, greater or fmaller, until the mod fuitable quantity is found. Suppofe 

 the wheel to be urged from L towards M, and the pendulum made to vibrate by external 

 impulfc. The pin N proceeding townrds L will ftrike the tail GO, raife the pallet A, - 

 and fct the wheel at liberty ; which Aiding along the inner furface of the pallet B, will raife. 

 it, and flop againfl: the claw at its lower end. I O will confequentiy be carried into the pofi- 

 tion IP ; and the pallet A in its return will be oppoHte a vacancy, which will permit the 

 tail GO to follow the pin N as far as the perpendicular fituation. The pendulum will 

 therefore be afllfled by the weight u through a longer arc in its defcent, than it was im« 

 peded by it in its afcent. In the oppofite femi-vibration towards M, the pendulum will 

 proceed unoppofed by v, while it pafles through the angle OIP, when it will raife B, and 

 permit the wheel to elevate the pallet A. In the motion on this fide of the perpendicular, 

 it is alfo clear that the defcent will be more aflifted than the afcent was impeded. 

 Whence it follows that the clock will continue to go : and no variation of the force of 

 the wheel LM, which raifcs the pallets in the abfence of the pendulum, will affefl the 

 vibration, except fo far as it rhay afford a variable refiftance at the detent or claw. 



From obferving that the detached efcapemcnts require a very ftrong firft mover*, and that 

 pendulum clocks meafure time with great accuracy by means of Graham's dead beat 

 efcapement, fig. 2, notwithftanding the influence of oil and fridion during the repofe of 

 the movement, I was induced to contrive an efcapement which fliould be as free as the 

 crown wheel efcapement, but have no recoil or aflion during the time of reft, nor any 

 tletent, nor require oil on its pallets. I made a drawing at the beginning of the year 1784, 

 which I ftiowcd to various mechanics at that time. It has fince been adapted to a clock 

 in my pofleffion, and has been going very freely for a year paft. Fig. 9 is a (ketch in 

 which GH reprefents a fteel wheel ; D and E are pallets of agate, with flat poliflied faces. 

 The pallet D is fixed to the lever DC, which is confined to its prefent fituation by the 

 loaded branch or arm CB refling on the flop k. The lever EC is alfo kept in its fituation 



• A pocket time-piece by Brockb,iiik, making 5 ribiationJ, or t| beats per fecond, the radius of whofe 

 balance was 0.35 incli, and arc dtfcribed by the external furface of the expanf:on pieces 0.45 inch radius, waj 

 maintained by a force which, on trial at the axis of the fufee, proved equal to 9I oz. troy, paffing through 

 12 inches in 14 hours. Another, of the fame dimenfions and conftruftioD, was driven by j i J oz. with the fame 

 daily fall. And a large box time-keeper of Arnold, beating half-feconds, with a balance of two radii, each 

 one inch long, was maintained by a like force of 113 ouncei. This is nearly as much as is required to afford 

 a femi-vibration of 31° in a clock, with a fcconds pendulum of 81b. by the common eight-day train with 

 Graham's efcapement (fig. 4. ), but tb.rce times as much as is required for a well made regulator. A common 

 watch with a balance 0.8 inch diameter, was found to have a maintaining power of 5|o«, f.Tlling daily through 

 ix iflchfrs 



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