in the art of war, a number of men posted at any palling, or a company of the guards who go on the patrol.

the navy, the space of time wherein one division of a ship's crew remains upon deck, to perform the necessary services, whilst the rest are relieved from duty, either when the vessel is under sail or at anchor.

The length of the sea-watch is not equal in the shipping of different nations. It is always kept four hours by our British seamen, if we except the dog-watch, between four and eight in the evening, that contains two reliefs, each of which are only two hours on deck. The intent of this is to change the period of the night-watch every 24 hours; so that the party watching from 8 till 12 in one night, shall watch from midnight till four in the morning on the succeeding one. In France the duration of the watch is extremely different, being in some places six hours, and in others seven or eight; and in Turkey and Barbary it is usually five or six hours.

A ship's company is usually clasped into two parties; one of which is called the starboard and the other the larboard watch. It is, however, occasionally separated into three divisions, as in a road or in particular voyages.

In a ship of war the watch is generally commanded by a lieutenant, and in merchant-ships by one of the mates; so that if there are four mates in the latter, there are two in each watch; the first and third being in the larboard, and the second and fourth in the starboard watch; but in the navy, the officers who command the watch usually divide themselves into three parties, in order to lighten their duty.

Watch, is also used for a small portable movement, or machine, for the measuring of time; having its motion regulated by a spiral spring. Watches, strictly taken, are all such movements as show the parts of time; as clocks are such as publish it, by striking on a bell, &c. But commonly the name watch is appropriated to such as are carried in the pocket; and clock to the large movements, whether they strike the hour or not. See CLOCK.

The invention of spring or pocket-watches belongs to the present age. It is true, we find mention made of a watch presented to Charles V. in the history of that prince; but this, in all probability, was no more than a kind of clock to be set on a table, some resemblance whereof we have still remaining in the ancient pieces made before the year 1670. There was also a story of a watch having been discovered in Scotland belonging to king Robert Bruce; but this we believe has turned out altogether apocryphal. The glory of this very useful invention lies between Dr Hooke and M. Huyghens; but to which of them it properly belongs, has been greatly disputed; the English ascribing it to the former, and the French, Dutch, &c. to the latter. Mr Derham, in his Artificial Clockmaker, says roundly, that Dr Hooke was the inventor; and adds, that he contrived various ways of regulation. One way was with a loadstone; another with a tender straight spring, one end whereof played backwards and forwards with the balance; so that the balance was to the spring as the bob to a pendulum, and the spring as the rod thereof: A third method was with two balances, of which there were divers sorts; some having a spiral spring to the balance for a regulator, and others without. But the way that prevailed, and which continues in mode, was with one balance, and one spring running round the upper part of the verge thereof: Though this has a disadvantage, which those with two springs, &c. were free from; in that a sudden jerk, or confused shake, will alter its vibrations, and put it in an unusual hurry.

The time of these inventions was about the year 1658; as appears, among other evidences, from an inscription on one of the double balance watches presented to king Charles II. viz. Rob. Hooke Inven. 1658. T. Tompion fecit, 1675. The invention presently got into reputation, both at home and abroad; and two of them were sent for by the dauphin of France. Soon after this, M. Huygens's watch with a spiral spring got abroad, and made a great noise in England, as if the longitude could be found by it. It is certain, however, that his invention was later than the year 1673, when his book de Horol. Oscillat. was published; wherein he has not one word of this, though he has of several other contrivances in the same way.

One of these the lord Broucker sent for out of France, where M. Huygens had got a patent for them. This watch agreed with Dr Hooke's in the application of the spring to the balance; only M. Huygens's had a longer spiral spring, and the pulses and beats were much slower. The balance, instead of turning quite round, as Dr Hooke's, turns several rounds every vibration.

Mr Derham suggests, that he has reason to doubt M. Huygens's fancy first was set to work by some intelligence he might have of Dr Hooke's invention from Mr Oldenburg, or some other of his correspondents in England; and this, notwithstanding Mr Oldenworth's attempt to vindicate himself in the Philosophical Transactions, appears to be the truth (a). Huygens invented divers other kinds of watches, some of them without any string or chain at all; which he called, particularly, pendulum watches.

Striking WATCHES are such as, besides the proper watch-part for measuring of time, have a clock-part for striking the hours, &c.

Repeating WATCHES, are such as by pulling a string, &c. repeat the hour, quarter, or minute, at any time of the day.

(a) To expect perfection in a work of this extent would be unreasonable, and we trust to the candour of our readers for their acceptance of our best endeavours: we hold ourselves much obliged to them for their communications of every remark which may enable us to render the Encyclopaedia Britannica more worthy of that most encouraging reception which it has met with from the Public. To the regular series of articles, the present Editor had once reason to believe that a Supplement was to be annexed, which should include not only those additions which have been made to the circle of the sciences during the progress of the work, but likewise such articles as he or his predecessor had, through their unremitting occupation or their ignorance, suffered to escape their notice. In that Supplement he would have corrected all such errors or mistakes in the work as might have been discovered by himself or pointed out to him by his Correspondents. But he is no Proprietor, and cannot announce the publication of a Supplement but as an event of great uncertainty. He is therefore much obliged to his highly respected friend and correspondent who has put it in his power at present to do justice to the memory of Dr Robert Hooke; one of the greatest ornaments of the Royal Society of London during the time of its infant state and juvenile vigour, and one of the most extensive and inventive geniuses that the world has ever seen.

In the article HAUTEFEUILLE, we ascribe to that author the invention of the regulating or balance spring of a watch, by which its motion is made as truly equable as by a pendulum. This is verified by the watches of Harrison, Arnold, and others, which do not deviate from equable motion above one second in several days. That the importance of this is acknowledged by the intelligent Public, is evident from the serious and repeated deliberations of the British Senate, and the high rewards which it has given to the makers of such watches; and we trust that this will appear to such of our readers as are not so much interested in mechanical performances a sufficient excuse for our anxiety to give the honour of the invention to its right owner. We had collected from our searches that Mr Huyghens had discovered, by his analysis of pendulous motions, what kind of motion would be produced by any kind of varying force, and that a force varying in the proportion of its distance from the place of rest would produce isochronous vibrations, whatever might be their extent; and had made experiments on the force of springs, and found them to vary according to this very law. In consequence of this, he saw that a balance-watch might be made to answer the same end with his cycloidal pendulum-clock, which he had been for several years trying to fit for the discovery of the longitude of a ship at sea, under the protection of the States of Holland and the court of France, having obtained a patent monopoly from the States and from Louis XIV. When, after repeated disappointments, he introduced his proposed watches, with sanguine hopes of their performance, but before any trial, and applied for such an extension of his patent as should also comprehend a balance regulated by a spring, he was opposed by the watch-makers. They had willingly acquiesced in his exclusive right to the pendulum-clock, which was entirely his own demeine; but they could not help considering this extension of his patent as an encroachment on a common which they had possessed from time immemorial. The opposition was general both in Holland. Watch.

This repetition was the invention of Mr Barlow, and first put in practice by him in larger movements or clocks about the year 1676. The contrivance immediately set the other artists to work, who soon contrived divers ways of effecting the same. But its application to pocket-watches was not known before King James the Second's reign; when the ingenious inventor above-mentioned, having directed Mr Thompson to make a repeating watch, was soliciting a patent for the same. The talk of a patent engaged Mr Quare to resume the thoughts of a like contrivance, which he had had in view some years before: he now effected it; and being pressed to endeavour to prevent Mr Barlow's patent, a watch of each kind was produced before the king and council; upon trial of which, the preference was given to Mr Quare's. The difference between them was, that Barlow's was made to repeat by pushing in two pieces on each side the watch-box; one of which repeated the hour, and the other the quarter; whereas Quare's was made to repeat by a pin that stuck out near the pendant, which being thrust in (as now it is done by thrusting in the pendant itself), repeated both the hour and quarter with the same thrust.

Of the Mechanism of a Watch, properly so called. Watches, as well as clocks, are composed of wheels and pinions, and a regulator to direct the quickness or slowness of the wheels, and of a spring which communicates motion to the

Holland and in France, and naturally came to the knowledge of Mr Hautefeuille. This person was conscious of a double right to oppose this encroachment, having also, though perhaps empirically, and without principle, discovered that a spring, applied to the balance of a watch, produced a surprising equability of vibration; and hoped by its means to produce a perfect isochronism. By Mr Hautefeuille's opposition the effect of the French patent was stopped for want of registration. The Dutch patent was however expedied, and trials were made. But their result was unfavourable; many things were wanting besides the true adjustment of the regulating power of the balance-spring. Scientific mechanics was then in its infancy, Galileo was dead, Newton was but beginning his glorious career; Huyghens therefore had few assistants.

The Royal Society of London was just founded, and Charles II. or his brother the duke of York, law, like a prince, how conducive their labours would be to public prosperity, and particularly to the improvement of navigation. The king therefore enjoined them to turn much of their attention to this object: he established the Royal Observatory at Greenwich for this express purpose; and the parliament held out encouragement for the discovery of the longitude. It was natural therefore for Mr Huyghens to look to this quarter for encouragement; and if any one will take the pains to compare the dates of Mr Huyghens's mathematical labours, after his dissertation on the pendulum, and his correspondence with the British literati, till he was elected member of the Royal Society, his private correspondence afterward with Mr Oldenburgh, a German, their secretary, and his public correspondence with him as secretary of the Society, he will observe the operation of something more than scientific zeal.

This correspondence, however, did not answer Mr Huyghens's hopes; for it informed him that the ground had been preoccupied by Mr Hooke, who had long before discovered, that a spring properly applied to a watch-balance would produce isochronous vibrations, and had also long ago applied for a Royal patent for the monopoly. The history of this application is curious, as a mere matter of anecdote; and it is instructive, while it is humiliating to human vanity, showing us, that even in the greatest characters, genius and talents, and noble and undoubted virtues, may exist along with some of our less honourable propensities, and cannot altogether hinder their operation. There never was a time in which it was more proper that every one of us should have a monitor, who should sometimes call out aloud to us, "Remember that thou art a man," than the present, when fanatic vanity, under the false and abused name of philosophy, is waging war with everything that is good or true, and threatens to plunge the cultivated portions of the human race into their former barbarism, with the horrid addition of the habits of savage atrocity; while the voice of religion, which would call us together as the children of one parent, is stifled amidst the yells of brother friends. We hope for indulgence, then, while we endeavour, in a few words, to make the history of this invention as clear as can be expected in a subject which does not so sensibly interest the public in general, and after such a long interval of time.

Mr Hooke, from his infancy, had a strong predilection for mechanics; he had also a strong propensity to system-making; and, from his first years of serious occupations, entertained a notion, that every thing might be formed into a system, and that nothing could be prosecuted with any well-founded prospect of improvement unless it was so treated. His amazingly comprehensive genius grasped at every thing which came under his observation; and he immediately began to form a system about it.—His writings are full of scraps of such systematic views; many of them, it must be acknowledged, hasty, inaccurate, and futile, but still systematical. He called them algebras, and considered them as having a sort of inventive power, or rather as means of discovering things unknown by a process somewhat similar to that art. He valued himself highly on account of this view of science, which he thought peculiar to himself; and he frequently speaks of others, even of the most eminent, as childishly contenting themselves with partial views of the corners of things. He was likewise very apt to consider other inventors as encroachers on his systems, which he held as a kind of property, being ferociously determined to prosecute them all in their turn, and never recollecting that any new object immediately called him off, and engaged him for a while in the most eager pursuit. His algebras had already given him many signal helps; and he had no doubt of their carrying him through in every investigation. Stimulated by this overgrown expectation, when a discovery was mentioned to him he was too apt to think and to say, that he had long ago invented the same thing; when the truth probably was, that the course of his systematic thoughts on the subjects with which it was connected had really suggested it to him, with such vivacity, or with such notions of its importance, as to make him set it down in his register in its own systematic place (for this was his constant practice, worthy of such a genius, and of immense service to all inquisitive men). But it was put out of his mind by some new object of pursuit. We, at this time, can hardly conceive the ardour with which every thing was treated in those youthful days of scientific novelty.

His favourite algebra, of which he frequently speaks as an invaluable treasure, and the source of all his reputation, was his Mechanical Algebra or Method of Mechanic Invention. He says, that no question in mechanics could be proposed to him, but he could quickly tell whether it were possible to solve it; and could get into the proper track for the solution. Unfortunately, the whole machine. But the regulator and spring of a watch are vastly inferior to the weight and pendulum of a clock, neither of which can be employed in watches. In place of a pendulum, therefore, we are obliged to use a balance (fig. 1) to regulate the motion of a watch; and a spring (fig. 2) which serves in place of a weight, to give motion to the wheels and balance.

The wheels of a watch, like those of a clock, are placed in a frame formed of two plates and four pillars. Fig. 3 represents the inside of a watch, after the plate (fig. 4) is taken off. A is the barrel which contains the spring (fig. 2); the chain is rolled about the barrel, with one end of it fixed to the barrel A (fig. 5), and the other to the fusee B.

When a watch is wound up, the chain which was upon the barrel winds about the fusee, and by this means the spring is stretched; for the interior end of the spring is fixed by a hook to the immovable axis, about which the barrel revolves; the exterior end of the spring is fixed to the inside of the barrel, which turns upon an axis. It is therefore easy to perceive how the spring extends itself, and how its elasticity forces the barrel to turn round, and consequently obliges the chain which is upon the fusee to unfold and turn the fusee; the motion of the fusee is communicated to the wheel C (fig. 5); then, by means of the teeth to the pinion c, which carries the wheel D; then to the pinion d, which carries the wheel E; then to the pinion e,

Unfortunately this perished in the burning of Gresham College, where Mr Hooke had apartments from the Royal Society; and he does not seem to have replaced it. It was perhaps, like the rest, nothing more than scraps. The Correspondent who favours us with these observations saw, in 1768, many papers of Mr Hooke's writings in the Society's archives, which had evidently been rescued from the flames, and had been in the possession of Mr Waller; part of which he published, and would have given more had he lived. Many of the leaves were scraps, perhaps single lines; many had dates; many of them were such as would be fragments of this mechanical algebra. Mr Hooke positively says, that it was by this system that he discovered the regulating power of a spring. And this brings us to the subject in hand, to which we hope the foregoing observations will not be thought too long a preface.

In 1655 he was admitted into the Invisible Society at Oxford, and was particularly patronized by Dr Ward, afterwards bishop of Salisbury, who instructed him in astronomy, and strongly recommended to his mechanical genius the discovery of some method of maintaining the vibrations of a pendulum, as of immense service to the astronomer. This Hooke accomplished immediately, and thought of using pendulum clocks for discovering the longitude at sea; and his method of mechanic inventions quickly led him, he says, to the discovery of the regulating power of springs as equivalent (nay, he says, superior) to that of gravity. This is remarkable; for it appears that he had at that time mathematics enough to inform him, that nothing would produce isochronous vibrations but an accelerative force proportional to the space to be passed through; a truth neither obvious nor easily come at; and that the accelerative action of gravity on a common pendulum was not exactly in this proportion; but he did not then know the mechanical properties of the cycloid, a discovery referred to do honour to Mr Huyghens. Our Correspondent farther informs us, that he recollects seeing, among the scraps of Mr Hooke's writings, words nearly to the following purpose: "To produce a translation of a moveable thus ——— or thus ——— in the same time, requires a pressing power thus ——— or thus ———." This will evidently appear to be a hasty expression of a force as the distance to be run through. He had found by experiments, made probably with other views, that the force of a spring was proportional to its deviation from its quiescent shape, and this whatever was its shape. Of this truth he now saw the value, and marked it in his register, and gave it to his friends, agreeably to the custom of the times, in the form of a cipher ce, ii, no, iii, ii, ii, ii, which was afterwards explained "Ut tensio, sic vis."

Mr Boyle was then his chief patron, and to him he communicated his scheme of measuring time accurately by a balance-watch regulated by a spring; and showed him watches so constructed, which performed with surprising accuracy. Immediately after the Restoration, Mr Boyle acquainted Lord Brouncker and Sir Robert Moray, the most eminent gentlemen of the age for mathematical learning, and for natural knowledge in general, with Mr Hooke's discovery and scheme; and those gentlemen encouraged him to apply for a patent, and even drew up a form for an act of parliament, to give him a profit on his invention by a duty on shipping. This draught was shown to the king, and he granted a warrant for a patent to Mr Hooke for 14 years; which warrant was in the possession of Mr Waller.

It appears that these gentlemen were so sensible of the merits of the invention, and so confident of its success, that they associated themselves with Dr Hooke in the prosecution of it. But in what respect they were to contribute, besides their influence in procuring the patent and the act of parliament, does not appear. There remained, however, in Mr Waller's possession several scrolls and drafts of a mutual agreement between them, to this effect: In one of them it was agreed, that if the profits should exceed £6000, Mr Hooke should have 3/4ths of the overplus; if it should be only £4000, he should have 3/4ths, &c., they having the rest; and that Dr Hooke should be declared the author and inventor. It is probable that they were to advance the money necessary for carrying on the trade of watchmaking.—Many alterations were made in the terms of agreement; and it appears, that before any thing definitive was done, Hooke was disgusted, because they insisted, that if they or any other person should fall on any way of improving on these principles, they should enjoy the benefit of it during the currency of the patent. This he flatly refused; saying, that it was facile inventis addere. It is probable that his manner of refusal, which never was gracious or polite, might offend persons of their rank, and contribute to put an end to the whole affair; for it never went farther, and Hooke became much more retentive and close than formerly.

But while things were on a friendly footing, there occurred sufficient proofs of Dr Hooke's being the author of the invention, and that even Mr Huyghens could hardly fail of knowing something of it when he was in England in 1663, ten or eleven years before he published his claim, and even before he had analysed the motion of pendulous bodies. In page 247 of the Society's Register, in 1663, mention is made of Hooke's watches for the pocket, where the motion is regulated by springs. Now Hooke, in his first watches, employed two opposite springs, straight, and acting on the balance. which carries the wheel F; then to the pinion f, upon which is the balance-wheel G, whose pivot runs in the pieces A called the potance, and B called a follower, which are fixed on the plate fig. 4. This plate, of which only a part is represented, is applied to that of fig. 3, in such a manner that the pivots of the wheels enter into holes made in the plate fig. 3. Thus the impressed force of the spring is communicated to the wheels; and the pinion f being then connected to the wheel F, obliges it to turn (fig. 5.) This wheel acts upon the pallets of the verge 1, 2, (fig. 1.), the axis of which carries the balance HH, (fig. 1.) The pivot I, in the end of the verge, enters into the hole e in the potance A (fig. 4.) In this figure the pallets are represented; but the balance is on the other side of the plate, as may be seen in fig. 6. The pivot 3 of the balance enters into a hole of the cock BC (fig. 7.), a perspective view of which is represented in fig. 8. Thus the balance turns between the cock and the potance c (fig. 4.), as in a kind of cage. The action of the balance-wheel upon the pallets 1, 2 (fig. 1.), is the same with what we have described with regard to the same wheel in the clock; i.e., in a watch, the balance wheel obliges the balance to vibrate backwards and forwards like a pendulum. At each vibration of the balance a pallet allows a tooth of the balance-wheel to escape; so that the quickness of the motion of the wheels is entirely determined by the quickness of the vibrations of the balance; and these vibrations of the balance and motion of the wheels are produced by the action of the spring.

But the quickness or slowness of the vibrations of the balance depend not solely upon the action of the great spring, but chiefly upon the action of the spring a, b, c, called the spiral spring (fig. 9.), situated under the balance H, and represented in perspective (fig. 6.) The exterior end of the spiral is fixed to the pin a, (fig. 9.) This pin is applied near the plate in a, (fig. 6.) the interior end of the spiral is fixed by a peg to the centre of the balance. Hence if the balance is turned upon itself, the plates remaining immovable, the spring will extend itself, and make the balance perform one revolution. Now, after the spiral is thus extended, if the balance be left to itself, the elasticity of the spiral will bring back the balance, and in this manner the alternate vibrations of the balance are produced.

In fig. 5, all the wheels above described are represented in such a manner, that you may easily perceive at first sight how the motion is communicated from the barrel to the balance.

In fig. 10, are represented the wheels under the dial-plate by which the hands are moved. The pinion a is adjusted to the force of the prolonged pivot of the wheel D (fig. 5.), and is called a cannon pinion. This wheel revolves in an hour. The end of the axis of the pinion a, upon which the minute hand is fixed, is square; the pinion (fig. 10.) is indented into the wheel b, which is carried by the pinion a. Fig. 11. is a wheel fixed upon a barrel, into the cavity of which the pinion a enters, and upon which it turns freely. This wheel revolves in 12 hours, and carries along with it the hour-hand. For a full account of the principles upon which watches and all time-keepers are constructed, we must refer our readers to a short treatise, entitled Thoughts on the Means of improving Watchers, by Thomas Mudge.

Watch-gaffers, in a ship, are gaffes employed to measure the period of the watch, or to divide it into any number of equal parts, as hours, half-hours, &c. so that the several stations therein may be regularly kept and relieved, as at the helm, pump, look-out, &c.