Page:Cyclopaedia, Chambers - Volume 2.djvu/1001

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Invention prefently got into Reputation both at home and abroad ; and two of 'em were lent for by the Dauphin of France.

Soon after this, Mr. Huygens's Watch with a Spiral Spring got abroad, and made a great a noife in England, as if the Longitude could be found by it. — Tis certain, however, that his Invention was later than the Year 1673, when his Book dc Horol. Ofcillat. was publifh'd ; wherein he has not one word of this, tho he has of feveral other Contrivances in the fame way.

One of thefe the Lord Brounker fent for out of France, where Mr. Huygens had got a Parent for 'em. — This Watch agreed with Dr. Hook's in the Application of the Spring to the Balance; only Mr. Httygens's had a longer Spiral Spring, and the Pulfes and Beats were much flower. The Balance, inftead of turning quite round, as Dr. Hook's, turns feveral rounds every Vibration.

Mr. Derham fuggefts, that he has reafon to doubt Mr. Httygens's Fancy was firft fet to work by fome intelligence he might have of Dr. Hook's Invention, from Mr. Olden- burg, or fome other of his Correfpondents in England : tho Mr. Oldenburg vindicates himfeif againft that Charge, in Philofophical 7ranfattions, N° 118. and 129.

Huygens invented divers other Kinds of Watches, fome of them without any String or Chain at all ; which he call'd particularly Pendulum Watches.

As it was in England that Watches had their firft rife 5 fo 'tis there, too, rhey have arriv'd at their greateft Perfection. — Witnefs that exceeding Value put on an Englijh Watch in all foreign Countries, and that vaft Demand made for 'em. Monfieur Savary, in his DiBion. de Commerce, pretends to match the French Watchmakers againlt the EngUjll. — -- He afferts, " That if the Englijh be in any Condition to " difpute it with 'cm, they owe it entirely to the great " Number of French Workmen, who took ftielter here upon " the Revocation of the Edict otNauts" He adds, "That " three fourths of the Watches made in England, are the " Work of Frenchmen." From what Authorities he fays this, we know not : But it need not be told Engiijhmen that it is falfej there not being one French Name, that we know of, among all our fam'd Watchmakers : nor, in the Bo- dy of Watchmakers, is there one eighth part French.

'Tis certain the French People prefer our Watches vaftly to their own 5 infomuch, that to have 'em with the moreeafe, a number of Englijh Workmen were invited over in 1719, and eflablim'd with great countenance at Verfailles, under the Di- rection of the famous Mr. Law. — But the Eftablifhment, tho every thing promis'd well for it, and the French Watch and Clockmakers feem'd undone by it, fell to the Ground in lefs than a Year's time. — M. Savary imputes its Fall, intirely, to that ftrong Prejudice of the French People in behalf of the Englijh Workmen, and to the Opinion that the Watches did not ccme from England. But the Truth is, the Work- men fent over being moll of 'em Men of loofe Characters, grew diffulute, quarrell'd with the Priefts, infult'ed the Ma- giftrates, and were difmifs'd, of neceffity.

Striking Watches, are fuch, as befides the proper Watch-^n, for meafuhng of Time, have a Clock-part, for ftrik'mg the Hours, &c.

Thefe are real Clocks ; only moved by a Spring inftead of a Weight. — Properly fpeaking, they are call'd Pocket -Clocks. See Clock.

Repeating Watches, are fuch as by pulling a String, &c. do repeat the Hour, Quarter, or Minute, at any time of the Day, or Nighr.

This Repetition was the Invention of Mr. Barlow, and firft put in practice by him in larger Movements, or Clocks, about the Year 1676. — The Contrivance {trait fet the other Artifls to work, who loon contriv'd divers ways of effecting the fame. But its application in Pocket Watches was not known before King Ja?nes the Second's Reign ; when the ingenious Inventor abovemenrion'd, having directed Mr. t rho?/2pfon to make a Repeating Watch, was foliciting a Pa- tent for the fame.

The Talk of a Patent engag'd Mr. ghiare to refume the Thoughts of a like Contrivance, which he had had in view fome Years before : He now effected it ; and being prefs'd to endeavour to prevent Mr. Barlow's Patent, a Watch of each kind was produe'd before the King and Council j upon Trial of which, the Preference was given to Mr. £>itare*s.

The Difference between 'em was, that Barlow's was made to Repeat by pufhing in two pieces on each fide the Watch- Box $ one of which repeated the Hour, and the other the Quarter: Whereas ^/tare's was made to repeat by a Pin that ftuck out near the Pendant ; which being thruft in, (as now 'tis done by thrufting in the Pendant it felf ) repeated both the Hour and Quarter with the fame thruft.

Watch-work, is that Part of the Movement of a Clock or Watch, which is defigned to meafure, and exhibit the Time on a Dial-Plate ; in contradiftin&ion to that Part which contributes to the ftriking of the Hour, &c. which is call'd Clcck-work. See Watch.

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The feveral Members of the Watch-^tt, are, i° 1 The Balance, confifting of the Rim, which is its circular Part ; and the Verge, which is its Spindle ; to which belong the two 'Pallets or Zeves, that play in the Teeth of the Crown- Wheel.

2, The Potence,ox Pottance, which is the ftrong Stud in P ocket- Watches, wherein the lower Pivot of the Verge plays, and in the middle of which, one Pivot of the Balance- Wheel plays $ the bottom of the Pottance is the Foot, the middle part the Nofe, and the upper part the Shoulder.

3°, The Cock, which is the piece covering the Balance.

4°, The Regulator, or Pendulum Spring, which is the fmall Spring in the new ¥ ocket- Watches, underneath the Ba- lance.

5, The Pendulum ; whofe Parts are, the Verge, "Pallets, Cocks, and the Bob.

6°, The Wheels ; which are, the Crown-Wheel, in Pocket Pieces, and the Swing-Wheel in Pendulums; ferving to drive the Balance or Pendulum.

8°, The Contrate Wheel, which is that next the Crown- " Wheel, &c. and whofe Teeth and Hoop lie contrary to thofe of other Wheels ; whence the Name.

9°, The great, or firji Wheel ; which is that the Fufy, ££>c immediately drives : after which are the fecond Wheel, third Wheel, ike.

Laftly, between the Frame and Dial-Plate, are, the Pi- nion of Report, which is that fix'd on the Arbor of the great Wheel ; and ferves to drive the "Dial-Wheel, as that ferves to carry the Hand.

theory, and Calculation of Watch-work.

Preliminaries necefTary to the calculating the Watch-yart of a Movement, are laid down under the Articles Movement and Clock-work.

Preliminary Rules common to the Calculation of all Move- ments, the Clock as well as the Watch--patts $ fee under the Article Movement.

Particular Rules for the Striking-part ; fee under the Ar- ticle Clock-work.

Thofe for the Watch-part we have from the Rev. Mr.Ztev- ham, as follow.

i°, The fame Motion, 'tis evident, may be perform 'd ei- ther with one Wheel and one Pinion, or many Wheels and many Pinions 5 provided the Number of Turns of all the Wheels bear the Proportion to all the Pinions, which that one Wheel bears to its Pinion : or, which is the fame thing, If the Number produced by multiplying all the Wheels together, be to the Number produe'd by multiplying all the Pinions together, as that one Wheel to to that one Pinion. — Thus, fuppofe you had occafion for a Wheel of 1440 Teeth, with a Pinion of 28 Leaves ; you may make it into three Wheels and Pinions, viz. 4) 36, 7 ) 8, 1 ) 5. For the three Wheels, 36, 8, and 5, multiply'd together, give 1440 for the Wheels ; and the three Pinions 4, 7, and r, multiplied together, give 28 for the Pinions. — Add, That it matters not in what order the Wheels and Pinions are fet, or which Pinion runs in which Wheel ; only for Contrivance-fake, the big- geft Numbers are commonly put to drive the reft.

2,, Two Wheels and Pinions of different Numbers may perform the fame Motion. — Thus, a Wheel of 30" drives a Pinion of 4, the fame as a Wheel of 45 a Pinion of 5 5 or a Wheel of 90 a Pinion of 10. — The Turns of each being 9.

3, If in breaking the Train into Parcels, any of the Quo- tients fhould not be liked ; or if any other two Numbers to be multiplied Together, are defir'd to be varied ; it may be done by this Rule. — Divide the two Numbers by any other two Numbers which will meafure them; multiply the Quo- tients by the alternate Divifors 5 the Product of thefe two laft Numbers found, will be equal to the Product: of the two Numbers firft given.-— Thus, if you would vary 36 times 8, divide thefe by any two Numbers which will evenly meafure them : So, 36 by 4, gives 9 $ and 8 by 1, gives 8 : now, by the Rule, 9 times 1 is 9, and 8 times 4, 32 5 fo that for 36x8, you have 32X9; each equal to 288. If you divide 36 by 6, and 8 by 2, and multiply as before, \ou have 24 X 12 = 36 x 8=288.

4, If a Wheel and Pinion fall out with crofs Numbers, too big to be cut in Wheels, and yet not to be alter'd by thefe Rules 5 in feeking for the Pinion of Report, find two Numbers of the fame, or a near Proportion, by this Rule : As either of the two given Numbers is to the other $ fo is 360 to a fourth. Divide that fourth Number, as alfo 360, by 4, 5, 6, 8, 9, 10, 12, 15, (each of which Numbers exactly meafures 360) or by any of thofe Numbers that brings a Quotient neareft an Integer. — As fuppofe you had 147 for the Wheel, and 170 for the Pinion ; which are too great to be cut into fmall Wheels, and yet cannot be redue'd into lefs, as having no other common meafure but Unity : fay, as 170 : 147 : : 3 6 ° '• 4i<^ Divide the fourth Number, and 360 by one of the foregoing Numbers; as 311 and $60 by 6, it gives 52 and 60 ; divide them by 8, you have 39 and 45 : and, if you divide 360 and

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