A few years ago, our modern improvers would have the joint transferred from the pillar plate to the brass edge, than which nothing worse could have been proposed. In the old way, the whole of the movement was kept in its place by the united assistance of the joint, and of the bolt and its spring ; whereas, in the other way, the movement had its sole dependence on the pins of the brass edge feet, from which it would be disengaged by violent exercise on horseback, &c.
From what has been said of the imperfections in watches, it may be seen, that they are inevitable, arising from a want of energy of mind in workmen, of which not one in a hun dred is possessed. Can it be supposed, that every new watch, which is purchased, is complete, and requires no assistance ? Whoever thinks so, must be disappointed. Persons of this description, on finding it not to go as they expected, bring it to a watchmaker, many of whom cannot put it in a better state than that in which the workman left it. But it is not brought to him with the view of any thing be ing done to it, but to see what is the matter with it ; never considering, that any irregular going or stopping must nn ply some fault or other, and is the very cause that brings them to the watchmaker. It does not follow, however, from this, that every watch which stops is badly executed; this will happen sometimes with those of the very best ex ecution, and frequently from an over-nicety of execution. On its being left with him, he takes it down, to examine what is wanting to make it keep time. The owner, on be ing told afterwards that it will cost so much to make it do what is required, strongly suspects, though he is polite enough not to say it, that there must be some imposition on the part of the watchmaker. Much is the trouble which many have of rectifying the faults of work given in to them, and thought to be complete, and much money is paid to others to have them rectified. We have known four guineas ,paid to a workman for doing a particular branch ; and not being executed to the satisfaction of the watchmaker, he has given half as much inure to another to have it corrected. There are as few excel in this art as in those of sculpture, painting, and engraving, which are called the fine arts, a name to which the other is equally entitled, but which labours under the gi eat misfortune that few or none are able to appreciate its merits.
The old 'scapement, even after the application of the pendulumspring, not giving that satisfaction which was required, induced Huygens and Hooke to think of other means of improving it, or to substitute a superior me chanism in its place. In this pursuit, the mechanical talents of Hooke stood conspicuously eminent over those of the justly celebrated Huygens.
Some of the movements of Huygens' watches, or time keepers, were much larger than those of our box chrono meters. The contrate wheel was cut into teeth of the same form as those of the common crown wheel, and made to 'scape with a verge of the usual kind. On the axis of
this verge was a sort of contrate or crown wheel, having teeth like the ordinary contratc wheel, which drove a pinion fixed on the axis of the balance. The verge, when 'scaping with its wheel, caused the balance to make several revolutions from every impulse on the pallets. Plate CCCII. Fig. 2. Some of them had no pendulum spring, having been made perhaps before its application. When the balance made several revolutions in every vibra tion, each being two seconds, this 'scapement would be but ill suited for the coils of a pendulum-spring. Those having the pendulumspring appeared about 1675. This was the origin of half-timing, upon seeing, when the pendulumspring was applied, that it made the balance give two vibrations in the same time that it gave one without it. About the same period, Dr Hooke brought into notice his watch with a new 'scapement ; which, for seventeen years before, he had been privately endeavour ing to improve. This was very different from the old crown wheel one, and as much so from that of Huygens. It had two balances, on the axis of each of which was a toothed wheel, pitching into one another. The verge or axis of these balances had each a pallet on it. The balancewheel was flat, having a few ratchet or saw-like teeth ; its arbor run in the frame, parallel to those of the balances, at a point equally distant from them ; the three points forming, as it were, the angles of an equilateral triangle. When a tooth of the balancewheel gave im pulse on one pallet, the other, by the p tching of the two wheels, was brought about to meet another tooth, (alter the wheel had escaped from the pallet on the opposite side,) in order to receive impulse in its turn. There was a pendulumspring on one of the balances, and the ohject of their being pitched together was to prevent the effects of external motion on them. while it served the double purpose of bringing alternately about the pallets, which still gave some recoil to the wheels by the reaction of the balances. Although this was a very ingenious contri vance for a 'seapoment, yet it appears not to have given that satisfaction which was expected from it, (probably from indifferent execution, which, from Sully's account, was the case,) and the old one was again adopted. How ever, some years afterwards, other artists, among whom was Dutertre, were attracted by this 'scapement of Dr Hooke's, and were led, from time to time, to make im provements on it. From it originated the duplex 'scape meta, which has of late years been so much in repute. A large old German clock had a 'scapement on the same principle as the above, of which the maker's name is un known. Dr Hooke's claim to his own 'scapement, remains however undisputed.