HOROLOGY. 



121 



I 

 facJocfc 



fcjVrTho- 



>ai Reid. 



itr 



I. 



1. 1. 



the oil on : t-, and the friction by the 



crutch or fork lulum rod, are done away by 



this arrangement The motion of the pendulum is kept 

 up entirely by the force of the spring part of the pal- 

 lets, independent of any impediment in the wheel 

 work, so long as it has force sufficient to raise up the 

 pallets readily and easily: this force may be considered 

 as permanent and invariable, and so should be the arc 

 described by the pendulum. If the length of the pen- 

 dulum and of the arc it describes are invariable, so 

 should be the time which is kept by the clock. Having 

 described the parts which compose this 'scapement. it 

 will cow be requisite to shew their node of action, 

 which is extremely simple. 



n the pendulum is set in motion, it will, by 

 means of either one or other of the screws d, unlock 

 the swing wheel ; which, in the drawing, is represent- 

 ed as being locked by one of its teeth on the nib or 

 detent part of the right hand pallet ; and the moment 

 when the wheel is unlocked, the tooth at the left hand 

 pallet is ready to press forward and raise up the pal- 

 Ut ; end, of course, it bends up the spring. Let the 

 pendulum be now brought to the right hand side, the 

 steel bar e will meet ith the screw </, and carrying it 

 or piuhing it <n, it will by this means unlock the 

 wing v! eel, and allow it to escape. At this it. 

 the whrrl tooth meeting with the pallet on th< 



'jl:il-n'i. .t;.l KrcriUwaj on tf.r r!j|.. h, ami r. , 



it up till it is stopped by the detent or paJlrt 

 Here the wheel is locked until the return of the pen- 



tat side, when it mil be again unlo 

 From the time of the unlocking at the right hand 

 pallet, till the sane takes place at the left nan.' 

 pendulum, during its rxrunion to the right, is opposed 

 by the spring part of the pallet*, and on its return it is as- 

 r tane part, until thr pendulum come* in con- 

 he point of the screw af on the left head part: 

 Here it is again opposed in its excursion, as far as 

 the arc it describes ; and on its descent or return, it 

 inpeiled by that of the spring part of 

 the pallet, in conjunction with the force of gravity. In 

 this clock, all that the motive force through the wheels 

 has to do, is to raise up the pallets, by bending up the 

 spring*, and these, along with gravity, maintain the 

 s^juisTi of tnc ptrTMiulurn. 



-n clocks of the common construction get foul in 

 the oil. or dirty, the arc of vibration (alls off, or is less 

 than what it was when the dock was dean and free. 

 In this tcapemcnt, however, when the dock gets fool, 



th.- f. r,.- .,t tl.r .: _ } , I t.,t!i. ,. t) . .1, -,,. t , - rt 



of the pallets, will be lessened, consequently the wheel 

 will more easily be unlocked by the prndufon : hence 

 we may expect a small e arc of vibra- 



tion ; but whether this will affect the thnekeepirg, by 

 making it slow, must be left to the experience of those 

 who nay think of making such trials. It appears to 

 list if any lengthening of the arc of vibration 

 takes place, it ill be equally accelerated by the greater 

 tension of the spring part of tl.e pallets. 



Another clock having the - of '*cspn&ent, 



has since been nade by Mr Thomas Reid, where the 



adjustment* for 'seansjsjttnt and beat are transferred 



the pallets to the r* ndulnv itself. By this means, 



'tineiit* are r,. t only raskr made, but are 



tfci-trtl v nger tow huh the pallets are 



i* done by the screws which are 



' 'scsptment has also been very advan- 



iven where a verge and crutch were 



adopted. 



The following is a scheme and description of another 

 oi. u. raxr r. 



clock acapemmt, which the writer of this article con- 



trivtd about twelve or fifteen years ago. _ 



In Plate CCCI. Fig. 3. SW is the swing wheel, An , lU .\ r 

 whose diameter may be so large, as to be sufficiently dock 

 free of the arbor of the wheel that runs into its pinion, 'icapenicni 

 which in eight day clocks is the third. The teeth of by Mr Beit 

 this swing wheel are cut thus deep, in order that the {V^iA-^. 

 wheel may be as light as possible, and the strength of . ?> ^ | 'j. 

 the teeth "little more than what is necessary to resist the 

 action or force of a common clock weight through the 

 wheels. They are what may be called the locking 

 teeth, as will be more readily seen from the use of them 

 afterwards to be explained. Those called the impulse 

 teeth, consult of very small tempered steel pins, inserted 

 on the surface of the rim of the wheel on one ide only. 

 They are nearly two-tenths of an inch in height ; and the 

 smaller they are, so much more room will be given to the 

 thickness of the pallets. If they have strength to sup- 

 port about eighty or a hundred grains they will be 

 strong enough. There is no ruU- required for placing 

 them relatively to the locking teeth, only they may 

 as well be opposite these teeth as anywhere else. 1', I' 

 are the pallets, whose centre of motion U the same with 

 that of the verge at a. These pallets are formed to 

 as to have the arms sufficiently rtrong, and at tin- 

 same time a* light as may be. That part where the 

 arms meet at the angle at a, has a steel socket made out 

 of the same piece as the arms, being forged together in 

 this manner. Thi socket is made to fit well on thr 

 -e, on which it i* only twisted fait ; and is turned 



Kiy mull on the outside, in order to allow the ar- 

 of the detents to be laid as dose to the verge as 

 may be, so that their centres of motion may coincide as 

 nearly as possible. A perfect coincidence oi' t ! > < ntres 

 might be obtained by using a hollow cylinder for the 

 verge, with the detent arbors running in the inside of 

 it, but this would have occasioned more trouble. That 

 part of the pallet frame, as it may be called, in which 

 u set the stone for receiving the action or impulse 

 of the small pin teeth, is formed into a rectangular 

 hape, so as to allow room for a dovetail groove, into 

 the stone pallets are fixed, as may be seen 

 at IT, Fig. 3. and at I', Fig. 4. which also gives a *"* * 

 ide view of the verge at a, and where the socket of 

 the pallets is seen as fixed on the verge. At 4, Fig. 

 4, is seen the outer end of one of the stone pallets 

 made flu.h with the steeL That part of the stone pal- 

 lets upon which the pin teeth act, may be seen in 

 3. where they are it presented in their respective po- 

 sitions relative to the pin teeth. Their shape or form is 

 exactly that which gives the dead beat. In Fig.3. are 

 seen the detents d, d, whose centre of motion is at c, c. 

 They are fixed on their arbors by a thin steel socket, 

 made as forged with the detents, much in the same way 

 as the pallets were, si may be Mrn at e, Fig. 5, which fig. *. 

 gives a side view of one of the detents and its arbor. 

 The screws tt,jj, in the arms of the detents, have a 

 place made to receive them, which is more readily seen 

 in Fig. 5. than in Fig. 3. The screws t, t, serve for the 

 purpose of adjuting that part of the **cap. nect- 



ed w ith the pallets, pushing the detenu out from locking 

 the wheel, by means of the locking >d* of 



the screws r, eon the unlocking, are met by the ends of 

 the stone pallets, cn- < t . i b, Fig. 4. 



The screw*/,/ serve toadjiivt the wheel 



teeth on the detents, g, g are bran rectangular pieces or 

 stud*, which are fixed to l;,r Ir.-nie 



plate, and may be near an inch in height 1 heend*o( the 

 screw*/ / rest on the tide of tl.ee tud, and according 

 as they are more or less screwed through at the ends of. 

 4 



