REMONTOIll. 



improvpments are made in mpchanical contrivances, by men 

 whole ui-incipal employment has no connection with the art 

 to the impruviMiicnt of which they contribute ; this was 

 probably the cafe with Mr. Antis, and is confelledly lo 

 with Mr. Mendham, who was rewarded with the filver 

 medal of the Adelphi Society, in the year 1807, (fee 

 vol. XXV. ) for a remontoir efcapcment for a chronometer, 

 which next offers itfelf for our defcription. Fij;s. 4, 5, 

 and 6, of Plale XLIl. are copied from the plate given by 

 Mr. Mendham, fig. 4. being a fedion of the whole elcape- 

 ment, fy. 5. a plan of the wheel and locking pallet, and 

 Jig. 6. a detached view of the pallets and their common 

 arbor. The letters a a, mfig. 4, are the two plates of the 

 frame that contain the works ; b is the balance, nearly of 

 the ufual (hape and fizc ; c is the pallet that acls with the 

 wheel, and d its arbor ; e is the locking fingle fpring ; and 

 f is the unlocking pallet in the form of a pin, attached 

 to c, and feen better in fig. 6. At the lower end of arbor 

 d is placed g, the remontoir-fpring, that gives force both 

 to the fmall pallet f, and alfo to the perpendicular pin h, 

 that forms a part of the pallet c. The arbor d docs not 

 alcend above the upper plate of the frame, but the pin h 

 does, and the plate being formed, as we fuppofe, like a 

 rim, h is jormitted to move in the vacant fpace within the 

 rim, and fufliciently high to fall in the way of the finer 

 pin /, inferted into and under the balance. The balance i 

 has its verge immediately over the upper pivot of arbor d, 

 point to point nearly, fo that the motions of the balancc- 

 piu /, and of the pin h, tliat impels it, may be concentric. 

 The cock k fupports the upper pivot of the verge, and 

 alfo holds the outer end of the balance or pendulum-fpring. 

 The aftion of thefe parts may be thus explained ; before 

 motion is given to the balance, we mufl conceive its pin t 

 to be in contaft, or nearly in contaft with the pin h of 

 the pallet c, and it muft be remembered, that the wheel 

 refts on the pallet during the vibration of the balance : fup- 

 pofe now that the remontoir-fpring g is in the aft of being 

 wound up by tlie balance-wheel, a-s aftuated by the train ; 

 and that the pin i of the moving balance has kept in contadl 

 with the impelling pin h, borne by the arbor of the remon- 

 toir, it is evident, that the force of the remontoir-fpring is 

 here oppofed to the momentum of the balance and at lall 

 flops it, thereby forming a banking of an unlimited extent ; 

 but the tooth of the wheel in contaft with pallet c, at the 

 point of Ihortell radius, alTifts to oppofe or wind up the 

 faid fpring during a fpace of one-fifth of a circle, till 

 the tooth has palled and the wheel is locked ; on the re- 

 turn of the balance the remontoir-fpring exerts all its force 

 on the balance, but without a jerk, the pins i and h being 

 already in contad, till it comes to the flop ; the balance 

 then maintains its motion, and the fmall pallet/ having un- 

 locked the wheel by forcing out the detent, the next tooth 

 of the wheel falls on the pallet c, and waits the return of 

 the balance, when the fame operation is repeated. 



Mr. Ramfay of lllington was confulted on the merits 

 of this efcapement, and, on confidering its properties, he 

 gave a written report to this effeft ; that the impulfe is here 

 given to the balance without fridion, exadly as in Mudge's 

 chronometer ; and that the remontoir is wound up by the 

 maintaining power in a fimilar way, except that the fhape 

 of Mudge's toolh limited the quantity of tenfion of the 

 .fpring, which here depends on the amount of the maintain- 

 ing power ; but that this efcapement, having but one re- 

 montoir-fpring, is more fimple than Mudge's, and allows 

 an unlimited arc of vibration, which advantages com- 

 penfate the foregoing difadvantage in the (hape of the 

 tooth ; and laiUy, that it is fuperior to the detached efcape- 

 3 



ment, inafmucli aj that it gives the impulfe without fric. 

 tion. 



C. Prior's. — The filver medal and twenty-five guineas 

 were voted to Mr. George Prior, junior, of Otiey, ir 

 V.orkfliire, in the year i8oy, by the Adelphi fociety (vol. 

 xxvii.) for his invention of a new clock efcapement, in which 

 an impelling (not however called a remontoir) fpring ac- 

 tuates, or profedes to actuate, the pendulum at each alter, 

 nate vibration. The account, particularly of the action, 

 as printed in the fociety's Tranfadtion':, feems to us fo extra- 

 ordinary, that we beg leav^ to tranfcribe it verbatim, in or- 

 der to make fome remarks on it, that may enable the reader 

 to judge of the efcapement's peculiar qualiti;-s, or at leall 

 of llie manner in which they are defcribed. Fig. 7. of 

 Plale XLII. already referred to, contains enough of thi 

 cicapement to anfwer the purpofe of the defcription in quel- 

 tion, and therefore we will omit the references to fig. i. in 

 tlie original plate, and attend to its^-. 2. only. " Fig. (j) is 

 a back view, which is fuppoled to be taken from behind the 

 clock ; a reprefents the axis of the fwmg-wheel, or lall 

 wheel of the train of the clock i I d is the fwing-wheel 

 fixed upon it, having thirty ferrated teeth ; it is turned 

 round, in the direction from i to d, by the maintaining power 

 of the clock ; ^^f is a fpring-detent, which locks againft one 

 ol the teeth of the fwing-wheel, and this prevents its run- 

 ning down by the action of the maintaining power; /j is 

 another fpring-detent, which is called the impelling fpring ; 

 when left at liberty, it unlocks the former, by pufhin;; 

 againll the end of the fmall arc e, failencd to the detent g, 

 and thus removing the end of the detent which obftructed the 

 wheel's motion ; / ij the rod of the pendulum, fufpcnd-ed bv 

 a cock fcrewed to the back plate of the clock ; a fmall 

 piece of brafs, i, projeds at right angles from the impel- 

 ling fpring /j, fo as to intercept the pendulum rod in its vi- 

 bration, and at this place a fmall fcrew is put through the 

 pendulum-rod /, the point of which moves the impelling 

 fpring back : a fmall pin is fixed to the frame, in a line be- 

 tween the point of fufpcnfion of the pendulum, and the 

 centre of the fwing-wheel, againll which the impelhng fpring 

 flops when at liberty. 



" Suppofing the pendulum to be vibrating backwards and 

 forwards, and the wheel locked as in the figure, the pendu- 

 lum fwinging from m to n, the impelling fpring h follows by 

 its elaflicity, until the pendulum / arrives at its perpendicu- 

 lar (or lowefl point of its arc) ; at this period the impelling 

 fpring comes lo rejl againll the end of the arc e, which it 

 pujlies back, fo as to releafe the tooth of the wheel from the 

 detent-fpring g ; the wheel now moves round a very fmall 

 fpace before it meets the end of the impelling fpring h, and 

 isjlopped thereby ; in the mean time the pendulum continues 

 its motion the extent of its vibration towards n, when it 

 returns, and arriving at the perpendicular, it meets the impel- 

 ling fpring h, and carries it along ivith it, until the tootii of 

 the wheel which rclls againll it efcapes from the end of it, 

 and another tooth of the wheel comes to relt againfl the 

 fpring-detent g. The fucceeding vibration of the pendu- 

 lum repeats the fame operation." This is the whole ac- 

 count, from which the reader is induced to believe that the 

 pendulum, and impelling fpring h, ad and re-aft on each 

 other ad infnitum, without any aid from the maintaining 

 power through the medium of the wheel, which is never 

 faid to raife, or otherwife to move the impelling (or remon- 

 toir) pallet, in order that it may, in its turn, impel the pen- 

 dulum by its acquired force. Again, it is faid, the impel- 

 ling fpring unlocks the detent g when it arrives at the per- 

 pendicular, or nearly, if not quite, at the point of its 

 quiefcence, where it has no force, and from that point, not 



the 



