HOROLOGY. 



147 



Hrp *: .- 



cbo. 



quiring pt^HMMM 

 naking it. 1 liis motion i* 



plan, ana nice execution in 



Making it. Thi* motion i* well adajvted for half quar- 

 ters: Though we have hardly seen u French repealer 

 with it, yet it is not unknown to the foreign artists, a* 

 appears from Thiout's work, torn. ii. p. 3d", plate xxxvi. 

 fig. 3. Paris, 1741. This repeating motion must have 

 got its name from the inventor. Upon inquiring after 

 when in London, in the year 1770, we learned, 

 much regret, that he had died a few months be- 

 fore in a charity work-house, at a very great age. The 

 name appear* Jo be German ; but whether be was a fo- 

 reigner or an ^Englishman, we have not been able to 

 learn. 



We shall now lay before our readers a complete de- 

 scription of the repeating movement and motion-work 

 of clocks and watches, which we have taken princi- 

 pally from Berthoud's Ettai rur L' Ilorlvgerie. 

 . . ' *': Clocks that have a striking pan, strike of themselves 

 Si* the hours, and some strike the hours and half hours ; 

 J^f but those having a repeating part strike only on a cord 

 and motion- being pulled, if it is a clock ; and if it is a watch, 

 verk. wha the pendant or pusher i* forced home ; thus two 



hammer* strike the hour and the quarter*, which the 

 bands point to on the dial. We shall see by the de- 

 scription of a repeating clock, bow this is produced ; 

 but before doing so, we shall give a general idea of this 

 ingenious mechanism, which ia nearly the same for a 

 clock as for a watch. 



In order to make a clock repeat the hour, (see Plate 

 Fig. 2.1 the cord X is drawn which is wound 

 :!.?. 1 round the pulley P, fixed on the arbor of the first 

 wheel of a particular wheel work, the sole object 

 of which i* to regulate the intervals between each 

 blow of the hammer. The arbor of this wheel has 

 on it a hook, which take* hold of the inner end of 

 the repeating inain-epring contained in the barrel 

 4. 3. On this arbor i* also a plain wheel G, 

 Fig. 1. having 13 pins in it which serve to raise the 

 hammer*, twdve of them for the hours, and three for 

 the quarters. The number of blows that the hour 

 hammer strike*, depend* on the greater or lea* course 

 which the pin wheel G is made to take when pulling 

 UM> CM<|, and this course depends itself on the hour 

 pointed at by the hand* on the dial. Thus, if the 

 4wn when it is twelve hour* and three quar- 

 ter*, the pin wheel is obliged to make an entire revolu- 

 tion ; at Uu* instant the repeating spring bring* it 

 back, in which course it make* the hammer give twelve 

 blow, for the hours, and then three for the quarter*. 

 To distinguish the quarter* from the hours, a second 

 hammer M added, which, with the first, make* a double 

 blow at each quarter. 



It must now be shewn by what mean* the course 

 b the put wheel take* i* regulated on the cord 

 being pulled, and how it is proportioned to the hour 

 which the hands point to on the , 



A wheel >. or minute wheel, of the dial work. Fig. 3. 



d 



has its arbor 



u-. (n tliis case, and in common, the repeating 



of the back of the nil. 



between the dial and foreplate of the 

 It carrie* the p< turns the 



star wheel. takes twelve hour* to go once r 



called the ko*r m.ul, di- 



vided into twelve parts tending to the centre of the star 

 wheel Each of these part* forms diOtroil depths, like a* 

 many steps, which gradually come nearer the < 



(lockand 

 Wattm* 



and which cr\e to regulate the number of the hours 

 which the hammer must strike. Tor this purpose the 

 pulley P carries a pinion a, which pitches in with a 

 portion of a wheel C, Fig. 2. called the rack. When 

 the cord is pulled, and the rack is in consequence 

 made to advance towards the snail, the arm b stops 

 on such a step of the snail as it may meet with in 

 it* course ; and, according to the depth of this step, 

 the hammer strikes a greater or less number of blo\vs. 

 It will strike only one hour if the arm b of the rack is 

 stopped on the step 1, the most distant one from the 

 centre, as then the pin wheel getting only one of its pins 

 engaged, the hammer strike* only one blow. If, on 

 the contrary, the step K'. which is the deepest and 

 nearest the centre, is met by the arm b in its course, 

 which cannot get there until the pin wheel shall have 

 made one turn, then the spring in the barrel bring- 

 ing it back, will cause the hammer to give twelve 

 blows. 



It remain* to be seen how the quarters, are repeated. PLATE 

 The piece t, Fig. 2. which turns the star wheel, and CCCV. 

 take* one hour to make a revolution, is carried by Fig. '- 

 another snail A (railed the quarter inuil,) formed by 

 four divisions, making three paths or steps, on one of 

 which, when the cora i* pulled, the arm Q of a piece 

 (jl), called the ,/kVger, place* itself, and according as 

 the step is nearer or farther from the centre of the snail, 

 the end I) of .the finger finds itself more or less aside 

 from the centre a of the pulley P; so that when the poll 

 of the cord i* finished, and the pulley return* by 

 the force of the spring in the barrel, one of it* four pin* 

 act. on this finger, namely, the one which it finds at a 

 distance from the centre a, which answers to the eleva- 

 tion of the arm U, and this it what determine* the 

 blow* for the quarter* : thus when the finger i* applied 

 on the pin nearest the centre of the pulley, the hour 

 hammer strikes only the number of hour* that the 

 nail L and the arm 6 of the rack hare determine.: 

 the finger i* placed on the second pin, it doe* not stop 

 the pulley till after the hour hammer has struck the 

 hour, then a quarter, and so on for the three quarter*. 

 Having thus given an idea of the essential parts of a 

 repeaUr, let u* now proceed to a particular description 

 of a complete repeating dock with an anchor 'scape* 



Plate CCCV. -Fig*. 1, 2, and 3. represent all the 

 part* of a repeating dock, seen in plan. Fig. 1. re- 

 u rater i U the wheel* and piece* rmitamerl within the an MM* 

 frame, or what are put between the two plates, with 'tar*mrnt. 

 the exception of the anchor A, which is placed in this T 1 ;*" 

 way, to shew the 'scapement. 



The wheels B, C, D, E, F, are those of the move- sT I' *' 

 It B is the barrel, which contain* the clock main- ' 



The great wbed ia fixed to the bottom of the 

 J, and pitches into the pinion of the wheel ( , 

 which M the great intermediate wheel. I) in the third 

 or the centre or minute wheel, t E the fourth wheel, or 

 that where the oontrate wheel was uiuaUy placed. F the 

 ratchet, or scapement wheel. The centre wheel I) 

 make* a revolution in an hour. The pinion on whidi 

 this wbed i* fixed, has it* pivot prolonged, which pas- 

 se* through the fore plate. Fig. 3. This arbor or , 

 Fig. 4. enter* spring tight into the cannon of the minute 

 pipe whed m. seen in perspective, Fig. 5. which make* 

 also, by thu means, a turn in an hour. 1 his cannon 

 carrie* the minute hand ; and its wheel m pitches into 



Ta pan tt is nistiing w*tfc. with UM U1 .hl.. . uadcr UM fMral I 

 jrkmcn fir. UM aasn* at niaaic wbctl to what Bothoud gim UM asm 

 -Wei, obttp. to nuke il the ctnttr or lIsWHKl, Ik coafcimity 10 



of UK */. Mr*. 



and lihc IU uumiautr 



