Mr Quare, an eminent watchmaker in London, had en tertained the same notion some years before, but not hav ing brought it to perfection, he thought no more of it until the noise excited by Mr Barlow's patent awakened in him his former ideas. He set to work, and finished his me chanism. The fame of it spread abroad among the watch makers, who solicited him to oppose Barlow's privilege to obtain a patent. They addressed themselves to the court ; and a watch of the invention of each was brought before the king and his council. The king, after having made trial of them, gave the preference to that of Mr Quare.
The difference between these two inventions is this : The repetition in Mr Barlow's watch was effected by push ing in two small pieces, one on each side of the watch case, one of which repeated the hour, the other the quarters. Quare's watch repeated by means of one pin only fixed in the pendant of the case, which, being pushed in, made the repetition of the hours and quarters, the same as is done at this present time, by pushing in once only the pendant which carries this pin.
This invention of repeating the hours in small fixed clocks, and in watches, was soon known and imitated in France ; and these machines were very common in 1728, when the celebrated Julien Le Roy was much occupied in their improvement. It was at this period that lie made the repeating clock, of which a description is given at the end of The Artificial Rule of Time. This was made for the bedchamber of Louis the Fifteenth of France.
The first repeaters, even those of Quare's, as well as others, gave the number of the hour according to the length pushed in of the pendant ; which was very incon venient, by striking any hour, whether the pendant was pushed home to the snail or not. This frequently caused mistakes, in regard to the true hour which ought to have been given. From the report of our predecessor, Mr James Cowan of this place, who went to Paris in 1751 for improvement in his profession, and who executed some pieces under Julien Le Roy, it was he who introduced the mechanism into repeaters, which prevented the watch from striking any thing but the true hour. This, we think, was done to the repeating- clock for Louis the Fifteenth's bed chamber. In this construction, unless the cord or pendant made the rack go fully home to the ail, it either struck :;one, or struck the true hour, which was a very considera lle Improvcmcli*. Thr piece employed for this purpose is called the all or nothing piece. Considering the gi eat talents which Julien Le Roy possessed, we have no reason to doubt of this improvement being his.
" Although the repetition," says Berthoud, " such as is now in practice, is a particular kind of striking, its me chanism differs totally from that of the striking clock ; 1st, Because every time that it is made to repeat, the main re peating spring is wound up; whereas, in the common strik ing part, the main-spring is wound up only once in eight days, fifteen, or a month : 2d, In the repetition we must substitute for the count-wheel, which determines the num ber of blows that the hammer must strike, a contrivance wholly different. The first author of this ingenious me chanism substituted for, the count-wheel a piece, to which, in regard to its form, he gave the name of the snail. The snail is a plain piece, divided into twelve parts, which form steps, and come gradually in from the circumference to wards the centre. It makes a revolution in twelve hours. Each of the steps is formed by a portion of a circle. Every time that the clock is made to repeat the hour, the pully which carries the cord is connected with and turns a pi nion, which leads a rack, whose arm falls on one or other of the steps of the snail, (on the cord being pulled,) and regulates the number of blows which the hammer ought to give ; and as this snail advances only one step in an hour, it follows, that if it is wanted to be made to repeat at every instant in the hour, we should have always the same number of blows of the hammer ; whereas, in setting off the wheel-work of an ordinary striking movement more than once in the hour, we should have a different hour. A count-wheel would then not be fit for a repetition. The mechanism of the repetition has a second snail, which bears four steps also in portions of a circle, to regulate the blows which the quarter hammers must give." The count and hoop wheels, and locking plate of the old striking clocks, for regulating the number of blows of the hammer, and locking the wheel-work, was excellently contrived. It had only one inconvenience, for when set off by accident, it would prematurely strike the hour to come: this made it requisite to strike eleven hours before it could be again brought to the hour wanted. Had it not been for the invention of the repeater, these would have continued, and would have been still made in the modern clocks, the same as in the ancient ones. But the snail of the repeater sheaved that it could be adapted for regulating the number of blows for the hammer of a common striking clock, and has prevented the inconvenience of striking over a num ber of hours, before the clock could he set to the right hour of striking.