CLOCK

, a machine now constructed in such a manner, and so regulated by the uniform motion of a pendulum, as to measure time, and all its subdivisions, with great exactness. Before the invention of the pendulum, a balance, not unlike the fly of a kitchen-jack, was used instead of it.—They were at first called nocturnal dials to distinguish them from sun-dials, which shewed the hour by the shadow of the sun.

The invention of clocks with wheels is ascribed to Pacificus, archdeacon of Verona, in the 9th century, on the credit of an epitaph quoted by Ughelli, and borrowed by him from Panvinius. Others attribute the invention to Boethius, about the year 510.

Mr. Derham, however, makes clock-work of a much older date; ranking Archimedes's sphere, mentioned by Claudian, and that of Posidonius, mentioned by Cicero, among machines of this kind: not that either their form or use were the same with those of ours; but that they had their motion from some hidden weights, or springs, with wheels or pulleys, or some such clockwork principle.

In the Disquisitiones Monasticæ of Benedictus Haëften, published in the year 1644, he says, that clocks were invented by Silvester the 4th, a monk of his order, about the year 998, as Dithmarus and Bozius have shewn; for before that time, they had nothing but sundials and clepsydræ to shew the hour.—Conrade Gesner, in his Epitome, pa. 604, says, that Richard Wallingford, an English abbot of St. Albans, who flourished in the year 1326, made a wonderful clock by a most excellent art, the like of which could not be produced by all Europe.—Moreri, under the word Horologe du Palais, says, that Charles the Fifth, called the wise king of France, ordered at Paris the first large clock to be made by Henry de Vie, whom he sent for from Germany, and set it upon the tower of his palace, in the year 1372.— John Froissart, in his Histoire & Chronique, vol. 2, ch. 28, says, the duke of Bourgogne had a clock, which sounded the hour, taken away from the city of Courtray, in the year 1382: and the same thing is said by Wm. Paradin, in his Annales de Bourgogne.

Clock-makers were first introduced into England in 1368, when Edward the 3d granted a licence for three artists to come over from Delst in Holland, and practise their occupation in this country.

The water-clocks, or clepsydræ, and sun-dials, have both á much better claim to antiquity. The French annals mention one of the former kind, sent by Aaron, king of Persia, to Charlemagne, about the year 807, which it would seem bore some resemblance to the modern clocks: it was of brass, and shewed the hours by 12 little balls of the same metal, which at the end of each hour fell upon a bell, and made a sound. There were also figures of 12 cavaliers, which at the end of each hour came out through certain apertures, or windows, in the side of the clock, and shut them again, &c.

The invention of pendulum clocks is owing to the happy industry of the last age; and the honour of that discovery is disputed between Galileo and Huygens. The latter, who wrote an excellent volume on the subject, declares it was first put in practice in the year 1657, and the description of it printed in 1658. Becher, De Nova Temporis dimetiendi Theoria, anno 1680, contends for Galileo; and relates, though at second-hand, the whole history of the invention; adding that one Trefler, clock-maker to the father of the then grand duke of Tuscany, made the first pendulum clock at Florence, under the direction of Galileo Galilei, a pattern of which was brought to Holland. And the Academy del Cimento say expressly, that the application of the pendulum to the movement of a clock was first proposed by Galileo, and put in practice by his son Vincenzo Galilei, in 1649. But whoever may have been the inventor, it is certain that the invention never flourished till it came into the hands of Huygens, who insists on it, that if ever Galileo thought of such a thing, he never brought it to any degree of perfection. The first pendulum clock made in England was in the year 1662, by one Fromantil, a Dutchman.

Among the modern clocks, those of Strasburg and Lyons are very eminent for the richness of their furniture, and the variety of their motions and figures. In the former, a cock claps his wings, and proclaims the hour: the angel opens a door, and salutes the Virgin; and the holy spirit descends on her, &c. In the latter, two horsemen encounter, and beat the hour upon each other: a door opens, and there appears on the theatre the Virgin, with Jesus Christ in her arms; the Magi, with their retinue, marching in order, and presenting their gifts; two trumpeters sounding all the while to proclaim the procession.

These, however, are far excelled by two that have lately been made by English artists, as a present from the East-India company to the emperor of China. These two clocks are in the form of chariots, in each of which a lady is placed, in a fine attitude, leaning her right hand upon a part of the chariot, under which appears a clock of curious workmanship, little larger than a shilling, that strikes and repeats, and goes for eight days. Upon the lady's finger sits a bird, finely modelled, and set with diamonds and rubies, with its wings expanded in a flying posture, and actually flutters for a considerable time, on touching a diamond button below it; the body of the bird, in which are contained part of the wheels that animate it as it were, is less than the 16th part of an inch. The lady holds in her left hand a golden tube little thicker than a large pin, on the top of which is a small round box, to which is fixed a circular ornament not larger than a sixpence, set with diamonds, which goes round in near three hours in a constant regular motion. Over the lady's head is a double umbrella, supported by a small fluted pillar not thicker than a quill, and under the larger of which a bell is fixed at a considerable distance from the | clock, with which it seems not to have any connection; but from which a communication is secretly conveyed to a hammer, that regularly strikes the hour, and repeats the same at pleasure, by touching a diamond button fixed to the clock below. At the feet of the lady is a golden dog; before which, from the point of the chariot, are two birds fixed on spiral springs, the wings and feathers of which are set with stones of various colours, and they appear as if flying away with the chariot, which, from another secret motion, is contrived to run in any direction, either straight or circular, &c; whilst a boy, that lays hold of the chariot behind, seems also to push it forwards. Above the umbrella are flowers and ornaments of precious stones; and it terminates with a flying dragon set in the same manner. The whole is of gold, most curiously executed, and embellished with rubies and pearls.

The ingenious Dr, Franklin contrived a clock to shew the hours, minutes, and seconds, with only three wheels and two pinions in the whole movement. The dial-plate has the hours engraven upon it in spiral spaces along two diameters of a circle, containing four times 60 minutes. The index goes round in four hours, and counts the minutes from any hour by which it has passed to the next following hour. The small hand, in an arch at top, goes round once in a minute, and shews the seconds. The clock is wound up by a line going over a pulley, on the axis of the great wheel, like a common 30 hour clock. Many of these very simple machines have since been constructed, that measure time exceedingly well. This clock is subject, however, to the inconvenience of requiring frequent winding, by drawing up the weight; as also to some uncertainty as to the particular hour shewn by the index.

Mr. Ferguson has proposed to remedy these inconveniences by another construction, which is described in his Select Exercises, pa. 4. This clock will go a week without winding, and always shews the precise hour; but, as Mr. Ferguson acknowledges, it has two disadvantages which do not belong to Dr. Franklin's clock: when the minute hand is adjusted, the hour plate must also be set right, by means of a pin; and the smallness of the teeth in the pendulum wheel will cause the pendulum ball to describe but small arcs in its vibrations; and therefore the momentum of the ball will be less, and the times of the vibrations will be more affected by any unequal impulse of the pendulum wheel on the pallets. Besides, the weight of the flat ring, on which the seconds are engraven, will load the pivots of the axis of the pendulum wheel with a great deal of friction, which ought by all possible means to be avoided. To remedy this inconvenience, the seconds plate might be omitted.

Mr. Ferguson also contrived a clock, shewing the apparent diurnal motions of the sun and moon, the age and phases of the moon, with the time of her coming to the meridian, and the times of high and low water; and all this by having only two wheels and a pinion added to the common movement. See his Select Exercises before mentioned. In this clock the figure of the sun serves as an hour index, by going round the dialplate in 24 hours; and a figure of the moon goes round in 24 h. 50 1/2 min. the time of her going round in the heavens from any meridian to the same meridian again. A clock of this kind was adapted by Mr. Ferguson to the movement of an old watch. See also a description and drawing of an astronomical clock, shewing the apparent daily motions of the sun, moon, and stars, with the times of their rising, southing, and setting; the places of the sun and moon in the ecliptic, and the age and phases of the moon for every day of the year, in the same book, pa. 19.

There have been several treatises upon clocks; the principal of which are the following. Hieronymus Cardan, de Varietate Rerum libri 17.—Conrade Dasypodius, Descriptio Horologii Astronomici Argentinensis in summa Templi erecti.—Guido Pancirollus, Antiqua deperdita & nova reperta.—L'Usage du Cadran, ou de l'Horloge Physique Universelle, par Galilée, Mathematicien du Duc de Florence.——Oughtred's Opuscula Mathematica.—Huygens's Horologium Oscillatorium.—Pendule perpetuelle, par l'Abbé de Hautefeuille.—J. J. Becheri Theoria & Experientia de nova Temporis dimetiendi Ratione & Horologiorum Constructione.——Clark's Oughtredus explicatus, ubi de Constructione Horologiorum.—Horological Disquisitions.—Huygens's Posthumous Works.—Sully's Regle Artisicielle du Temps, &c.—Serviere's Recueil d'Ouvrages Curieux.—Derham's Artificial Clock-maker.— Camus's Traités des Forces Mouvantes.—Alexandre's Traité Général des Horologies.—Also Treatises and Principles of Clock-making, by Hatton, Cuming, &c. &c.