Although an Englishman, Sully's name was unknown to his countrymen; and would have remained so, had it not been for the accounts given of him by the French artists, in whom he excited an emulation, and whom he inspired with a taste to acquire such a pre-eminence in their pro fession as had been before unknown to them. Julien le Roy, who was intimately acquainted with Sully, and Ber thoud, are uncommonly lavish of their encomiums on him. Soon after he had completed his apprenticeship with Mr Gretton, watchmaker in London, he went over into Hol land, Germany, and Austria, and attracting the notice of several of the princes and nobility, he was much employed by them. Having seen, in the library of Prince Eugene, the Memoirs of the Royal Academy of Sciences of Paris, he eagerly acquired the French language in order to read them. This excited in him a strong desire to see Paris, to which he repaired about the year 1713 or 1714, under the patronage, and in the suite of the Duke of Aremburg, at whose hotel he lodged, with a pension of 600 livres. He had not been long there, when our countryman, Law of Lauriston, under the authority of the court of Versailles, got him engaged to establish a manufactory of clocks and watches. In consequence of this he came twice to Lon don, and having carried away a great number of workmen at a vast expence, and spent much money on tools and other articles, Law began to murmur, and the establish ment in two years or little more fell to the ground. This made him complain bitter ly of his bad fortune to a friend ; but fortunately a nobleman to whom this was mentioned, feeling much for the disagreeable situation in which Sully was placed, sent him in a present sonic shares in the pub lic funds, value 12,000 livres, which enabled him, for seve ral years afterwards, to pursue very zealously his favourite scheme of making a marine time-keeper to ascertain the longitude at sea. In this attempt lie was not so successful in his first trials, as lie had led himself to expect. It was in general believed, however, that had he lived he would have been the first to have deservedly acquired one or other of the premiums which were before that time offer ed, by four of the greatest maritime powers in Europe, to those who produce a time-keeper which could as certain, to a certain extent, the longitude at sea. Philip the Third, who ascended the throne of Spain in 1598, was the first who proposed a reward of 1000 crowns for this invention. Tholates of Holland soon after followed his example, and offered 100,000 florins. The British Parlia ment, in the reign of Queen Anne, voted 20,0001. sterling for the same purpose ; and the Duke of Orleans, Regent of France, in 1716, promised, in the name of the King, 100,000 livrcs. Sully may literally be said to have died a martyr to the cause in which he was engaged. Having got a false address to a person who it was said was occu pied in the same pursuit with himself, he got so overheated in his anxious and vain endeavours to find him out, that he died in a few days after at Paris, in the month of October 1728, and was buried with great pomp in the church of St Sulpicius. Sully acted so conspicuous a part in the pro fession, that no apology is necessary for giving this short account of him.
It may be observed here, that Debaufre's 'scapement has this advantage, which is not in Graham's, that the im pulse is given the same in every vibration ; and the time of rest on both sides is the same, bearing mostly on the foot pivot end, and a little on the sides of the pivots, and not wholly on the sides of the pivots, as in Graham's. Hiving made one or two watches, to which this 'scape ment was put, they were found to perform very well ; and we would recommend it to the attention of 'scapcment makers : A little practice will make the execution of it very easy. The two thin steel wheels may at pleasure be placed at any distance from one another ; their diameters should be as large as can be admitted between the potence foot and the verge collet. An agate, or any hard stone, for the pallet, whose height is half the spaces between the teeth, or a little less, is fixed on the verge or axis of the ba lance ; the level of the base of the pallet on which the teeth rest being a very little above that of the line of the centre of the balance wheel pinion. The teeth must be a very little un dercut, so that the points only may rest on the pallet. The verge should be placed more inward in the frame than in the common contrate wheel movement, in order to give room for the balance wheels. The necessity of a contrate wheel movement for this 'scapement is a trifling objection, which will wear away in spite of prejudice.
In 1722, the Abbe Hautcfeuille, who long before this had at Paris disputed, in a process of law with Huygens, the right of the invention and application of the pendulum spring to the balance of a watch, published a quarto pam phlet, containing a description of three new constructions of 'scapements for watches. One of these was the anchor,
or recoiling 'scapcment, on the verge of which was at tached a small toothed segment of a circle, or rack, working into a pinion, which was the axis of the balance. Plate CCCII. Fig. 5. The idea of the axis of the balance be ing a pinion, seems to have been taken from the 'scape ment of Huygens, with this difference only, that the ba lance should not make so many revolutions as that of Huy gens, and is contrived so as to make scarcely one revolution at every vibration. This 'scapement is the same as it came from the hands of Hautefeuille, without any im provement having been made upon it even to this day, al though a patent was taken out for the same invention above twenty years ago, by some person in Liverpool. The name of lever watches, which they received from the patentees, is that which is generally given to those having this 'scapement, which is the same that Berthoud has de scribed in his Essai sur l'Horlogerie, published in 1763 ; see torn. ii. No. 1933, and plate xxiii. fig. 5, of which our Figure is a copy. Berthoud, under certain modifications, introduced the principle of this 'scapement into some of his marine time-keepers.
A very able and ingenious artist at Paris, M. Dutertre, who was zealous in his profession, and had considerable success in his pursuits, invented, in 1724, a new 'scape ment, or rather improved that of Dr Hooke's with two ba lances, which has already been described. Plate CCCII. Fig. 6. The additions and improvements, however, which he made, were so great, as to give him a sort of title to claim it as his own, and to render it, in the opinion of good judges, the best 'scapement by far that was known at that time. The additions which he made, consisted in putting another wheel upon the same arbor with the first, but it was considerably larger in diameter, having the same num ber of teeth with the other, and forming the principal merit of the 'scapement. The balance arbors at one place were made rather thicker than usual, for the purpose of having notches cat across them, and as deep as to the centre. This part of the arbors becomes then a setnicylinder. The larger wheel, which may be called that of arritc, or repose, is placed on its arbor, so as to correspond with the semi cylinders and their notches, the points of whose teeth arc made just to clear the bottom of the notches, alternately passing one of them, and resting on the semicylindrical part of the other. The action of the two wheels shall now be explained. Let us suppose, that one of the larger wheel teeth, after reposing on one of the semicylinders, is, on the return of the vibration of the balance, admitted to pass through the notch ; after having passed, a tooth of the im pulse-wheel falls on the corresponding pallet, gives im pulse, carrying it on till it escapes ; when another tooth of the wheel of repose falls on the other semicylinder, and rests there until the return of the vibration of the other balance ; when it passes the notch in its turn, and the corresponding pallet presenting itself, is impelled by a tooth of the impulse wheel, and so on. Hooke's 'scape ment had a small recoil ; the aim of Dutcrtre was to make a dead beat one of it, in which he succeeded. There is a drawing of this 'scapcment in Plate xiv. fig. 4. of Berthoud's Histoire de la illesure du Tenzits. He says, tt that the properties of this 'scapement are such, that sudden shocks do not sensibly derange the vibra tions ; that the pressure of the wheel-teeth of arrete on the cylinders, corrects the impulse that the balance receives from the wheel work, which, on the motive force being doubled, prevents the vibrations from being affected." In Plate xli. fig. 16. of the first volume of Thiout's work, is a drawing of this 'scapement, modelled for that of a clock, described at page 101. He says, " Fig. 16. is an escapement of the Sicur Jean Baptiste Dutcrtre, which has only one pallet, on the axis of which is the fork. The two ratchets or wheels are on the same arbor, when the pallet escapes from the small ratchet ; the larger one, which is called the ratchet, or wheel of' arrete, rests on the arbor of the pallet, and leaves the %ibration to be pretty free. Plate CCCII. Fig. 7. On the pallet's returning to meet with the teeth of the small ratchet, the pallet-arbor, or cylinder, being notched or cut across into the centre, allows the wheel of arrete to pass; and the w heel of impul sion, after getting a small recoil, gives new force to the vibration ; so that in two tibrations only one of them is accelerated : Hence it was thought, that the half of Ore vibrations being free, and independent of the wheel work and its inequalities, they would be more correct than others ; but experience did not confirm this." This is, then, the duplex 'scapcment, or the nearest possible ap proach to it.