134 



HOROLOGY. 



.Mudge's 

 detached 

 'scapement. 



PLATE 

 CCCIII. 

 Fig. S. 



called the lifting tpring, which cannot be too delicate, 

 but is made a little thicker towards the outer or lifting 

 end than anywhere else. This end of the lifting spring 

 projects a very little beyond that of the detent spring. 

 On the arbor of the roller and balance, and placed near 

 the roller, is twisted a short and thick steel socket, in 

 which is set a bit of precious stone, the face of which 

 is made flat, and nearly in a line with the centre, be- 

 hind it is chamfered on towards the point, and made 

 rather thin than otherwise. This is called the l>ft'! 

 pallet. The length or height is made so as to unlock 

 the wheel to the best advantage, that is, by only 

 carrying the detent a short way beyond the unlocking. 

 This excursion is to be confined to as small an angle 

 as may be. Near to the detent piece is fixed a stud, 

 in which is a screw to regulate the depth of the detent 

 into the- wheel teeth. The point of the screw should 

 be hardened, and have a part of the ruby detent to 

 rest upon it, when the detent spring presses that way. 

 When the balance is at rest, the face of the lifting 

 pallet is very near to the outer side and end of the 

 lifting spring. If the balance is brought a very lit- 

 tle about to the left, the lifting pallet will pass the end 

 of the lifting spring. On the balance being now turn- 

 ed towards the right, at the moment of the wheel being 

 unlocked, the main pallet or roller presents itself, to re- 

 ceive the point of one of the teeth, and is impelled with 

 considerable force ; meanwhile the detent falls again to 

 its place, and locks the wheel. The balance having com- 

 pleted this vibration, returns. In the returning, the lift- 

 ing pallet pushes the lifting spring easily aside, being no 

 longer supported by the detent spring when turning 

 in this direction, that is, from the right to the left, the 

 detent is again ready to be disengaged on the next re- 

 turn of the balance to the right, and so on. 



The detached 'scapement of Mudge was contrived 

 about sixty years ago or thereabouts, if we may reckon 

 from the year 1766', when he showed it to Berthoud, 

 who was then in London, and who informs us that it 

 had been made a considerable time before. 



This 'scapement consists of a wheel and pallets, like 

 those made for the dead beat 'scapement of a clock, on- 

 ly the wheel teeth are not cut half the depth. On the 

 verge or arbor of the pallets is placed an arm of any 

 length, generally a little more than that of the pallets. 

 The end of the arm is formed into a fork-like shape. 

 On the axis of the balance is a short pallet, whose act- 

 ing end may be of a small circular form, having the 

 sharp part of the angles blunted, coming a little way 

 within the prongs of the fork, which alternately acts, 

 and is acted upon. There is also on the balance axis a 

 small roller, having a notch in it. On the end of the 

 arm is attached a small steel piece or index, in a plane 

 which may be either above or below the prongs of 

 the fork ; this index is on the outside of the roller, 

 when the free part of the vibrations is performing, 

 and prevents the wheel teeth from getting away from 

 the place of rest. On the return of the balance, the in- 

 dex passes with the notch in the roller to the opposite 

 side. Meanwhile the short pallet gets into the fork, 

 meeting with one of the prongs, pushes it on a very 

 little way, and thus disengages the teeth of the wheel 

 from the circular part of the pallet, where they rest du- 

 ring the free excursions of the balance. During the dis- 

 engaging, the teeth get upon the flanch of the pallet, 

 and give impulse, which causes the opposite prong of the 

 fork to come forward on the short pallet, and commu- 

 nicate impulse to it. In Mudge's 'scapement, as drawn in 

 the plate lor the work published by his son, there are two 



short pallets, and the prongs of the fork He in different K-cape- 

 planes. The impulse in this 'scapement is given at ^ menu. 

 every vibration ; and it seems to have done uncommon- X ~"'Y"'" 1 ' ' 

 ly well, particularly in the watch which he made for 

 her Majesty Queen Charlotte. It is by no means suit- 

 ed for the execution of ordinary workmen, as it re- 

 quires more address than usually falls to their share. 

 The late Emery was much taken up with it ; and al- 

 though he had a little success, and had the aid of a very 

 excellent hand, yet he experienced considerable difficul- 

 ties. It might be somewhat easier managed, by adopt- 

 ing Lepaute's mode of Graham's dead beat, which we 

 have tried. 



In 1792, a very neat and ingenious detached 'scape- jiowciu* 

 ment was contrived by the late Howells, founded on detached 

 that of Kendal's, (in whose hands he had occasion fre- 'scapement. 

 quently to see it,) in which the wheel teeth rested on 

 the cylindrical part of the pallet, during a part of the rrrm 

 going and returning vibrations of the balance. See Fig. p iR 6 

 6. In the other, after impulse is given on the face of the 

 same semicylinder, and just before the tooth is quitting 

 it, a detent is presented to receive one of the wheel teeth, 

 by which the action of the wheels is suspended during 

 the greater part of the going and returning vibrations, 

 the pallet being then free and independent of the 

 wheels. This 'scapement is composed of two crown 

 wheels on the same arbor, the points of the one being 

 opposite to the middle of the spaces of the other. On 

 the axis or verge of the balance, which stands quite 

 close to that of the balance wheels, is a semi-cylindri- 

 cal pallet, whose diameter should be according to the 

 angle of 'scapement required, which will also regulate 

 the distance of the wheels from each other. The pallet is 

 put near to the collet on which the balance is rivetted; 

 a small arbor, having very fine pivots, is run in so as 

 to stand parallel with that of the balance, and placed 

 at some distance outside of the wheels, but where a 

 line drawn from it, and passing at equal distances from 

 the points of the wheel teeth, when continued, shall 

 fall in with the centre of the balance ; on this arbor is 

 fixed an arm, at the end of which is a small fork and 

 index ; on the verge or balance axis, and near the lower 

 end, is a short pallet, and a roller connecting with the 

 fork and index, in imitation of Mudge's, acting in the 

 same way as has been described, but only in the lock- 

 ing and unlocking part. Where the arm passes between 

 the wheel teeth, which may be at ninety degrees or so 

 from where they act on the pallet, are fixed two detent 

 pieces, one for each wheel ; opposite to the arm, and 

 in the same line. A part of it is prolonged beyond the 

 arbor outside, by way of a counterpoise, where two 

 screws in fixed studs serve here as a banking to it. It 

 may easily be conceived, that one of the wheels being 

 locked, suppose that on the left, the balance, when re- 

 turning from the left to the right, will, by means of the 

 short pallet and forked arm, &c. carry the detent away ; 

 and just as the point of the tooth is free, the face of the se- 

 micylinder is presented, to meet with a tooth of the same 

 wheel and get impulse ; but before this tooth has nearly 

 escaped, the detent is ready to receive a tooth of the op- 

 posite wheel, and so on. This 'scapement gives an im- 

 pulse at every vibration, as is done in Mudge's. In 

 the tenth volume of the Transactions of the Society for 

 the Encouragement of Arts, SfC. there is a description 

 and drawing of it. It may be observed, that were 

 the semicylindrical pallet faced with a piece of pre- 

 cious stone, the 'scapement would go on for a consi- 

 derable time without falling off 



In the marine keepers which Mr Mudge himself 



