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Get on your night-gown, lest occasion call us, British seamen, if we except the dog-watch, beAnd shew us to be watchers.

Id. tween 4 and 8 P.M., that contains two reliefs, each Call home our exiled friends,

of which are only two hours on deck. The intent That fled the snares of watchful tyranny.

Id.

of this is to change the period of the night watch Hie thee to thy charge ;

every twenty-four hours; so that the party watchUse careful watch, chuse trusty centinels.

1.

ing froin eight till twelve in one night, shall watch Turn him into London streets, that the watchmen

from midnight till 4 A. M. on the succeeding one. might carry him before a justice.

Bacon. Love can find entrance not only into an open heart,

In France the duration of the watch is, or was, but also into a heart well fortified, if watch be not well extremely different, being in some places six hours, kept.

Id. and in others seven or eight; and" in Turkey and Up unto the watchtower get,

Barbary it is usually five or six. A ship's comAnd see all things despoiled of fallacies. Donne. pany is usually classed into two parties, one of

When by God's mercy in Christ, apprehended by which is called the starboard, and the other the faith, our hearts shall be purified, then to set watch and larboard watch ; it is, however, occasionally seward over them, and to keep them with all diligence. parated into three divisions, as in a road or in par

Perkins. ticular voyages. In a ship of war the watch is The experience of our own frailties, and the considera.

• generally commanded by a lieutenant, and in mertion of the watchfulness of the tempter, discourage us.

Hammond,

chant ships by one of the mates ; so that, if there

indoe thuself are four mates in the latter, there are two in each Watch over thyself, counsel thyself, judge thyself ar impartially.

Tavlor watch; the first and third being in the larboard, All night he will pursue ; but his approach

and the second and fourth in the starboard watch; Darkness defends between, till morning watch. Milton. but in the navy, the officers who command the Sleep, listening to thee, will watch.

Id. watch usually divide themselves into three parties, A watch, besides the hour of the day, gives the day to lighten their duty. of the month, and the place of the sun in the zodiac. Watch is also used for a small portable move

Hale. ment or machine for the measuring of time, having He is bold, and lies near the top of the water, watch its motion regulated by a spiral spring. Watches, ing the motion of any water-rat that swims betwixt strictly taken, are all such movements as show the him and the sky.

Walton.

parts of time; as clocks are such as publish it by It is observed by those that are more attentive watchers

More striking on a bell, &c. But commonly the name of the works of nature.

watch is appropriated to such as are carried in the Nodding a while, and watchful of his blow, He fell; and falling crushed the ungrateful nymph be- pocket, and clock to the large movements, whether low.

Dryden. they strike the hour or not. See Clock. Readers should not lay by that caution which be - Watch Work. The regulator of a clock or comes a sincere pursuit of truth, and should make them watch is a pendulum or a balance. Without this always watchful against whatever might conceal or mis- check to the motion of the wheels, impelled by a represent it.

Locke. weight or a spring, the machine would run down 'Smithing comprehends all trades which use forge or with a motion rapidly accelerating, till friction and file, from the anchor-smith to the watchmaker ; they all the resistance of ihe air induced a sort of uniforusing the same tools, though of several sizes. Moron.

mity, as they do in a kitchen jack. But if a penAn absurdity our Saviour accounted it for the blind

dulum be so put in the way of this motion, that to lead the blind, and to put him that cannot see to the office of a watch.

South.

only one tooth of a wheel can pass it at each vibraAll the long night their mournful watch they keep,

ful watch they keen. tion, the revolution of the wheels will depend on And all the day stand round the tomb and weep.

the vibration of the pendulum. This has long been

Addison. observed to have a certain constancy, insomuch Love, fantastick power ! that is afraid

that the astronomers of the east employed penduTo stir abroad till watchfulness be laid,

lums in measuring the times of their observations, Undaunted then o'er cliffs and valleys strays,

patiently counting their vibrations during the And leads his vot'ries safe through pathless ways. phases of an eclipse or the transits of the stars, and

renewing them by a little push with the finger when Husbands are counselled not to trust too much to they became too small. Gassendi, Riccioli, and their wives owning the doctrine of unlimited conjugal others, in more recent times, followed this example. fidelity, and so to neglect a due watchfulness over their The celebrated physician Sanctorius is the first manners.

Arbuthnot. The bullet, not having been extracted, occasioned

person who is mentioned as having applied them

person great pain and watchings.

Wiseman's Surgeru. as regulators of clock movements. Machines. The melancholy tune of a watchman at midnight. however, called clocks, with a train of toothed

Swift. wheels, leading round an index of hours, had been Prejudices are cured by a constant jealousy and contrived long before. The earliest of which we watchfulness over our passions, that they may never have any account is that of Richard of Wallingford, interpose when we are called to pass a judgment. abbot of St. Alban's, in 1326. It appears to have

Watts. been regulated by a fly like a kitchen jack. Not Watch, in the art of war, a number of men long after this, James Dondi made one at Padua, posted at any passage, or a company of the guard: which had a motus succussorius, a hobbling or who go on the patrole.

trotting motion ; from which expression it seems Watch, in the navy, the space of time wherein probable that it was regulated by some alternate one division of a ship's crew remains upon deck movement. We cannot think that this was a pento perform the necessary services, whilst the rest dulum, because, once it was introduced, it never are relieved from duty, either when the vessel is could have been supplanted by a balance. Galiunder sail or at anchor. The length of the sea- leo proposed the pendulum, about the year 1600. watch is not equal in the shipping of different Pendulum clocks then came into general use, and nations. It is always kept four hours by our were found to be greatly preferable to balance

clocks, as accurate measurers of time. Mathemati- will destroy that isochronism, unless it be so applied cians saw that their vibrations had some regular that the sum total of this impulsion and the force dependence on uniform gravity, and in their writ- of gravity may vary so with the situation of the ings we meet with many attempts to determine the pendulum, as still to give a series of forces, or a law time and demonstrate the isochronism of the vibra- of variation, perfectly similar to that of gravity. tions. Riccioli, Gassendus, and Galileo, made This cannot be effected, unless we know both the similar attempts to explain the motion of pendu- law which regulates the action of gravity, produclums, but without success. This honor was reserv- ing isochronism of vibration, and the intensity of ed for Mr. Huyghens, the most elegant of modern the force to be derived from the wheels in every geometers. He had succeeded in 1656 or 1657 in situation of the pendulum. The necessary requiadapting the machinery of a clock to the maintain- site for the isochronous motion of the pendulum is, ing of the vibrations of a pendulum. Charmed that the force which urges it toward the perpendiwith the accuracy of its performance, he began to cular, be proportional to its distance from it; and investigate with scrupulous attention the theory of therefore, since pendulums swinging in small circuils motion. By the most ingenious and elegantlar arches are sensibly isochronous, we must infer application of geometry to mechanical problems, that such is the law by which the accelerating action he demonstrated that the wider vibrations of a pen- of gravity on them is really accommodated to every dulum employed more time than the narrower, and situation in these arches. that the time of a semicircular vibration is to that of Under the head of CLOCK-MAKING we have a very small one nearly as thirty-four to twenty entered very fully into the construction of those nine; and aided by a new department of geome. large horological machines that are intended to meatrical science invented by himself, viz. the evolu- sure the time by means of a weight and pendulum. tion of curves, he showed how to make a pendulum In watches, on the contrary, a spring is the usual swing in a cycloid, and that its vibrations in this curve maintaining power. are all performed in equal times, whatever be their From what we have already seen of the nature extent. But before this time Dr. Hooke, the most of the pendulum, it will be apparent that its oscilingenious and inventive mechanician of his age, lations can only approach to a true measure of had discovered the great accuracy of pendulum time when the point of support is fixed and imclocks, having found that the manner in which they moveable. An approximation, however, to this dehad been employed had obscured their real merit. sideratum may be obtained by a pocket watch They had been made to vibrate in very large arches, regulated by a balance. This useful machine, in the only motion that could be given them by the its most perfect form, contains within itself a co.contrivances then known; and in 1656 he invent- lection of inventions which have exercised the skill ed another method, and made a clock which moved of some of the most ingenious mechanics for the with astonishing regularity. Using a heavy pen- three last centuries, and it is gratifying to kuow dulum, and making it swing in very small arches, that we are indebted to our countrymen Hooke, the clocks so constructed were found to excel Mr. Graham, Earnshaw, Arnold, and Harrison, for its Huyghens's cycloidal pendulums. It has been invention and present improved form. found that the unavoidable inaccuracies, even of To explain the mechanism of a watch it is necesthe best artists, in the cycloidal construction, make sary to refer to the figs. 1, 2, 3, plate Watches, as the performance much inferior to that of a common they contain engravings of a sunk pocket-watch of pendulum vibrating in arches which do not exceed the best construction. Fig. 1 is a plan of the wheelthree or four degrees from the perpendicular. Such work all exhibited at one view, for which purpose clocks alone are now made, and they exceed all the upper plate of the watch is removed." Fig. 2 expectation. We have said that a pendulum need is a plan of the balance, and the work situated ed only to be removed from the perpendicular, and upon the upper plate. Fig. 3 is an elevation of then let go, in order to vibrate and measure time. all the movements together, the works being supHence it might seem that nothing is wanted but a posed to be opened out into a straight line, to exmachinery so connected with the pendulum as to hibit them all at once. keep a register, as it were, of the vibration. It The principal frame for supporting the acting could not be difficult to contrive a method of doing parts of the watch consists of two circular plates, this : but more is wanted. The air must be dis- marked C and D in the figures ; of these the placed by the pendulum. This requires some former is called the upper plate, and D is called force, and must therefore employ some part of the the pillar plate, from the circumstance of the four momentum of the pendulum. The pivot on which pillars, E, E, which unite the two plates and keep it swings occasions friction-the thread or thin them a proper distance asunder, being fastened piece of metal by which it is hung, in order to firmly into the lower plate; the other ends pass avoid this friction, occasions some expenditure of through holes made in the upper plate, C, and force by its want of perfect flexibility or elasticity. small pins, being put through the ends of the pilThese, and other causes, make the vibrations grow lars, keep all together; but, by drawing out these more and more narrow by degrees, till at last the pins, the whole watch may be taken to pieces ; pendulum is brought to rest. We must therefore, and the pivots of the several wheels being received have a contrivance in the wheel-work which will in small holes made in these plates, they of course restore to the pendulum the small portion of force fall to pieces as soon as the plates are separated. which it loses in every vibration. The action of The maintaining power is a spiral steel spring, the wheels therefore may be called a maintaining which is coiled up close by a tool used for the pure power, because it keeps up the vibrations. But pose, and put into a brass box called the barrel: we now see that this may affect the regularity of it is marked A in all the figures ; the pivots of its vibration. If it be supposed that the action of gra- arbor pass through the top and bottom of the barvity renders all the vibrations isochronous, we must rel, and one of them is filed square to hold a ratchet grant that the additional impulsion by the wheels wheel ), which has a click, and retains the arbor from turning round except in one direction; the assemblage of wheels is called the train of the two pivots of the arbor are received in pivot holes watch. The great wheel, G, has forty-eight teeth in the plates C, D, of the watch, and the pivot which on its circumference, which take into and turn a has the ratchet wheel upon it passes through the pinion of twelve teeth, fixed on the same arbor plate, and the wheel marked b, with its click, is with the centre wheel H, so called from its situa Therefore on the outside of the pillar plate D of the tion in the centre of the watch ; it has fifty-four watch; the top of the barrel has a cover or lid teeth to turn a pinion of six leaves, on the arbor fitted into it, through which the upper pivot of the of the third wheel I, which has forty-eight teeth; arbor projects; thus the arbor of the barrel is to it is sunk in a cavity formed in the pillar plate, and be considered as a fixture, the click of the ratchet turns a pinion of six, on the arbor of the conwheel preventing it from turning round, and the trate wheel K, which has forty-eight teeth cut interior end of the spiral spring being hooked, this parallel with its axis, by which it turns a pinion of arbor is stationary likewise. The barrel thus mount- six leaves, fixed to the balance wheel L; one of ed has a small steel chain, d, coiled round its cir- the pivots of the arbor of this wheel turns in a cumference, and attached to it by a small hook of frame, called the pottance, fixed to the upper plate, the chain which enters a little hole, made in the cir- and the other pivot runs in a small piece fixed to cumference of the barrel at its upper end; the the upper part, called the counter pottance (not other extremity of this chain is hooked to the lower shown in any of the figures), so that when the two part of the fusee, marked F, and the chain is dis- plates are put together, the balance wheel pinion posed either upon the circumference of the barrel, may work into the teeth of the contrate wbeel, as or in the spiral groove cut round the fusee for its is shown in fig. 4. The balance wheel, l, has fifreception, the arbor of which has pivots at the teen teeth, by which it impels the balance op; the ends, which are received into pivot holes made in arbor of the balance, which is called the verge, has the plates of the watch; one pivot is formed square two small leaves or pallets projecting from it, nearly and projects through the plate, to adapt the key by at right angles to each other; these are acted upon which the watch is wound up.

by the teeth of the balance wheel l in such a manIt is evident that, when the fusee is turned by the ner that, at every vibration, the balance receives a watch-key, it will wind the chain off the circum slight impulse to continue its motion, and every ference of the barrel on itself; and as the outer vibration so made suffers a tooth of the wheel to end of the spring is fastened to the barrel, and the escape or pass by; whence this part is called the other is hooked to the barrel arbor, which, as before escapement of the watch, and constitutes its most mentioned, is prevented from turning by the click of essential part. The wbeel l is sometimes called the ratchet wheel, a b, beneath, the spring will be the scape wheel, or crown wheel. Suppose the coiled up into a smaller compass than before, and, pinion h on the arbor of the balance wheel, or by its reaction, will, when the key is taken off, crown wheel, i k, to be actuated by the main spring turn the barrel, and by the chain turn the fusee which forms the maintaining power, by means of and give motion to the wheels of the watch, which the train of wheel-work in the direction of the will be hereafter described. The fusee has a spiral arrow, while the pallets m and n, attached to the groove cut round it, in which the chain lies; this axis of the balance, and standing at right angles to groove is cut by an engine, in such a form that the each other, or very nearly so, are long enough to chain shall pull from the smallest part or radius of fall in the way of the ends of the sloped teeth of the fusee, when the spring is quite wound up, and the wheel, when turned round at an angle at 45°, therefore acts with its greatest force on the chain; so as to point to opposite directions, as in the from this point the groove gradually increases in tigure; then a tooth in the wheel below, for indiameter, as the spring unwinds and so acts with stance, meets with the pallet n (supposed to be at less power, the chain operates on a larger radius of rest), and drives it before it a certain space, till the the fusee, so that the effect upon the arbor of the end of the tooth escapes ; in the mean time the fusee, or the cog-wheel attached to it, may always balance, os pr, attached to the axis of the pallets, be the same, and cause the watch to go with regu- continues to move in the direction rosp, and winds larity.

up the small spiral or pendulum spring 9, one end To prevent too much chain being wound upon of which is fast to the axis, and the other to a stud the fusee, and by that means breaking the chain on the upper plate of the frame; in this operation or overstraining the spring, a contrivance called a the spring opposes the momentum given to the guard gut is added; it is a small lever, e, moving balance by this push of the tooth upon the pallet, on a stud fixed to the upper plate, C, of the watch, and prevents the balance going quite round, but, and pressed downwards by a small spring, f; as the instant the tooth escapes, the upper pallet, m, the chain is wound upon the fusee, it rises in the meets with another tooth at the opposite side of spiral groove, and lifts up the lever until it touches the wheel's diameter, they therefore moving in an the upper plate, and it is then in a position to in- opposite direction to that below; here this pallet tercept the edge or tooth, g, of the spiral piece of receives a push which carries the balance back inetal seen on the top of the fusee, and thus stops again (having as yet but little power in the direcit from being wound up any further.

tion os pr), and aids the spring, which now unThe power of the spring is transmitted to the bends itself till it comes to its equiescent position, balance by means of several toothed wheels, which but it swings beyond that point, partly by the immultiply the number of revolutions that the chain pulse from the maintaining power on the pallet m, nakes on the fusee, to such a number, that though and partly by the acquired momentum of the 'the last or balance wheel turns nine times and a moving balance, particularly when this pallet, m, half every minute, the fusee will at the same time has escaped ; at length the pallet n again meets turn so slowly that the chain will not be all drawn with the succeeding tooth, and is carried backward off from it in less than twenty-eight or thirty hours, by it in the direction in which the balance is now and it makes one turn in about four hours ; this moving, till the maintaining power and force of Vol. XXII.

20

The time the fourth wheel revolves in.

centre-wheel teeth. Numbers for the

or counter-
Fourth wheel pinion.
| Third-wheel teeth.

wheel.
Escapement-wheel-

pinion.
| Escapement-wheel.
Number of beats in

one hour.
OOO
ooa

O OO
oooooooooooooooooo | Third-wheel pinions.

eigenen

OOO OO O
oooooooooooooooo
OOOOOOOooo

gemeente het e

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ihe unwo und spring together overcome the momen- Trains for plain Watches, with Eleven Teeth in the tum of the balance, during which time the recoil

Escapement-wheel. of the balance wheel is apparent (for the seconds hand of the watch is usually put on the pivot of the arbor of the contrate wheel); at length the wheel brings the pallet ne back again till it escapes, and the same process takes place with pallet m as has been described with respect to pallet n; thus two contrary excursions or oscillations of the balance take place before one tooth has completely escaped, which is the reason there must always be an odd number of teeth in this wheel, that a space

11179669 36 seconds. on one side of the wheel may always be opposite

17820 40 do. to a tooth on the other, in order that one pallet may

11 177953 384 do. be out of action during the time the other is in

11 17626,239 do. action.

(11 175333 39712 The upper pivot of the verge is supported in a

1117490 40 do. cock screwed to the upper plate, as shown at N,

1117391 3837 which covers the balance, and protects it from vio

11 17226 417 lence, and the lower pivot works in the bottom of

11/172202 4033 the pottance, M, at t. The socket for the pivot

11 171981 4048 do. of the balance wheel is made in a small piece of

11 17160 40 brass, v, which slides in a groove made in the pot

11 171413 394 tance, so that, by drawing the slide in and out, the

111708535389 teeth of the balance wheel shall just clear one pallet

1116940 37143 before it takes the other; and in the perfection of

1116874 4039 this adjustment, which is called the scaping of the

(11 16870 40 watch, the performance of it very greatly depends.

6 11 16775/3992 do. We shall speak more fully of this in another place.

6 11 16632 42% The banking of the watch is to prevent the balance

do. from being turned round too far by accidental jerks, in which case one of the pallets would be Trains for plain Watches, with Thirteen and Fifpitched upon the point of a tooth of the balance teen Teeth in the Escapement-wheel. wheel, and recoil it back too far, perhaps injuring its point; this is called being overthrown. Sometimes, if the balance gets turned round too far, the pallets are both turned away from the teeth of the wheel, which then runs down with inconceivable rapidity, and probably breaks the points of its teeth by striking against the pallets as they turn round; to avoid these accidents the banking is introduced ; it is a pin fixed in the rim of the balance, and therefore describing a circular arc round the edge of the cock N, which covers the balance; but the

1317914 454 seconds.

6 13 1786239 43247 do. proper extent of this arc is determined by the banking-pin meeting two projecting parts of the

6 13 177479 433 cock, which are extended out so far as to reach be

0 (1317680 424 do. yond the circle the banking pin moves in.

13/1756944515 Having thus examined the various parts of a

13 17505444337

113 17472 1438 watch, it may now be advisable to revert more particularly to the movement; the mode of arranging

1317454 425 the parts of which will be best understood by re

1317238 463 ference to a series of tables, calculated to produce

6 13/17225 455 any number of beats that may be required for

13 171889 452 practical purposes.

13 16900 4673 In the following tables the first column of figures

6 13 168454 453 do. gives the number of teeth in the centre, or second

6 1316796 447 do. wheel, to the different trains; the second column

6 13165993 4516% do. the number of leaves in the third-wheel pinion;

13 1658774463703 the third column the number of teeth in the thirdwheel; the fourth column the number of leaves For Fifteen Teeth in the Escapement-wheel. in the counter, or fourth-wheel pinion; the fifth column the number of teeth in the counter-wheel;

54 6 506

15/18000 44 do. the sixth column the number of teeth in the escape

6 15173337 49% do. ment-wheel pinion; the seventh column the num | 54 | 6 48 648

48 6 1517280 150 do. ber of teeth in the escapement-wheel; the eighth column the number of beats in the hour; and the ninth column the time the fourth, or counter- In the foregoing trains, pinions of seven are ipwheel, revolves in. These columns, if taken in troduced to perform seconds as pinions of eight or the line from left to right, give each train in suc- six, which complete fifths of seconds, two-ninths of cession.

seconds, and fourths of seconds. Few believe that

The time the fourth wheel revolves in.

do

centre-wheel teeth.
Third-wheel teeth.

wheel.

Fourth, or countereenen | Numbers for the

pinion. | Escapement-wheel

one hour.

Number of beats in

e a co | Escapement-wheel.
oooooooooooooo | Third-wheel pinions.
OOOOOOOOOOOOOOO | Fourth wheel pinion.

AAero

A
meer er een er en er en
ooOOOOOOOOOO
OTA A en care

pinions of seven will perform minutes, seconds, will come into action with the escapement pinion. &c., equal to pinions of eight or six. The following Then, to find how many revolutions will be given calculation will, however, prove it, and the same to an escapement pinion of seven, divide the 4200 rule is accurate and concise for every other calcu- teeth by the pinion of seven. lation.

7) 4200 teeth, divided by 7, The number of the centre-wheel teeth sixty, di- gives 800 revolutions to the escapement vided by seven, the number of the third-wheel

pinion in one hour. pinion, shows how many revolutions and parts are Then, an escapement-wheel with fifteen teeth, algiven to the third wheel, while the centre wheel lowing two beats for every tooth, makes thirty beats makes one revolution.

in each revolution; afterwards the question follows, 7) 60

how many beats in one hour ?

600 revolutions in the escapement

pinion, Eight revolutions, and four-seventh parts, are given Multiplied by 30 beats in each revolution, gives to the third wheel and pinion in one hour; then,

60) 18000 beats in an hour, divided by 60, if the third wheel has forty-nine teeth in it, the

gives the quantity of beats in question follows, how many teeth (repeated) of the

one minute. third wheel will fall in action with the fourth wheel

60) 500 the quantity of beats in a minute, pinion in one hour? 49 teeth in the third wheel,

divided by 60, gives the quan

tity of beats in one second. Multiplied by 84 revolutions in it,

5 the number of beats in one

second. 28

It may now be advisable to give the calculations 392

which govern the turns for the chain on the fusee. 420 teeth,

The first or great wheel, and the centre pinion, the number which fall in action with the fourth

are to be numbered to give the quantity of turns,

as follows: wheel pinion in one hour; the fourth-wheel pinion being seven, divide the 420 teeth by that number, to see how many revolutions will be given to the

Number of the Number of the Number of turns fourth-wheel pinion in one hour.

great wheel teeth. centre pinion. 1 in the fusee. 7) 420 teeth, divided by 7

48

12

12

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10

10

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is 60 revolutions given to the fourth wheel and pinion in one hour;

12

54 consequently must perform a minute circle. And here it follows to consider true seconds :

12 they have no regulation from the foregoing calculation, after it has produced sixty revolutions, by the fourth-wheel pinion, in one hour; therefore the fourth-wheel, escapement-pinion, and escapement-wheel, are to govern the seconds and parts of seconds. There can be no true seconds performed upon the minute circle without the parts of seconds be first considered.

First, fifths of seconds require 18,000 beats in one hour; secondly, two-ninths of seconds, which

10 perform two seconds in nine beats, allowing four

10 beats and a half for every second, which cuts the first second with the fifth beat, and coincides with

10 the second second at the ninth beat; and so on, successively, through the minute, cutting the odd,

10

10 and coinciding with the even numbers, which require 16,200 beats in the hour; and thirdly, fourths

70 of seconds require 14,400 beats in the hour. No other number of beats, between 18,000 and 14,400, The rule for examining the foregoing calculations will give exact parts of seconds. Manufacturers must be tried as follows :-The number of hours who have not these numbers can neither give a required for the watch to go must be first consitrue second nor a true minute : for the conclusion dered; say thirty hours; then the number of the of the minute will be cut by a fractional part, more centre pinion must be given, say twelve ; then mulor less, until so many minutes are performed as tiply the hours by the centre pinion, which product there are parts in the integer. But to give 18,000 being divided by the number of the great-wheel beats in the hour, for fifths of seconds, first it is to be teeth, say sixty; the quotient will be the turns of considered that the fourth wheel has sixty revolu- chain the fusee should have to perform thirty hours: tions in one hour; then, with seventy teeth in the for example : fourth wheel, how many teeth of the fourth wheel

30 hours, multiplied by will come into action with the escapement pinion ?

12 the number of the centre pinion. 60 revolutions, Multiplied by 70 teeth, in the fourth wheel

60) 360 product, divided by 60, the number

of the great-wheel teeth. 4200 teeth

6 quotient, the turns for the fusee chain,

10

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