CLOCK, in horology, is a machine which measures time with a degree of accuracy that gives it a just preference over the clepsydra, and other methods anciently used for the same purpose.
See CLEPSYDRIE.
The sphere of Archimedes, made two hundred years before the birth of Christ, is usually considered as the first attempt at the formation of a clock; it had, indeed, a maintaining power, but, being without any kind of regulator, could only measure time as a planetarium exhibits the motion of the stars, with relative, but not with positive precision.
In 1232, a machine for measuring time was sent by the Sultan of Egypt to the Emperor Frederic II. but this, if it had any regulating part, most probably had none superior to the flyer of a common roasting jack. Wallingford, at the begin ing of the fourteenth century, and Dondi, at the end of the same, have each had the honour of being supposed the first inven tors of clocks ; the account given of Don di's clock by Petrus Paulus Vergerius Vit. Princip. Carrar. torn. 16.) makes it nearly similar to our church clocks; as, like them, it was placed on the upper part of a turret, or steeple, and spontaneously pointed out each of the twenty-four hours in succession. There is still, however, some doubt whether Dondi was the origi nal inventor.
Boethius, at the end of the fifth century, Pacificus, about the middle of the ninth, and Gerbert, at the end of the tenth, are also regarded as the inventors of clocks, but on rather doubtful authority.
There are many documents to prove the-existence of clocks, with wheels and weights, in the middle of the fourteenth century, and therefore there is more rea son for assigning this period to the inven tion than any other.
On comparing the various testimonies relative to the origin of the clock,the fair est conclusion seems to be, that it is nei ther of so ancient a date as some writers suppose, nor yet among those more recent inventions which are placed in the last two centuries; and that the first inventor is not certainly known.
The opinion of Fer. Berthoud, who has written more on the subject of clock-work than any other man, is evidently most just, which asserts, that the clock is not the in vention of any one man,but an assemblage of successive inventions, each of which is worthy of a separate 1. Wheel work. which was known in the time of Archimedes ; 2. the application of the weight as a maintaining power; 3..i a use of the fly as a regulator ; 4. the ratchet wheel and click ; 5. the, substitution of the balance for the fly; and the escape ment, which was necessarily introduced at the same time ; 6. the application of the dial and hands : and 7. the addition. of the striking part.
In the clock which was placed in a tow er of the palace of Charles V. in 1364, by Henry de Wick, the regulating part consisted of a balance, which vibrated backwards' and forwards by an escape ment like that of common watches ; it had no balance spring, but this deficien cy was in some measure soppFed by the mode in which it was made to move ; its arbor was vertical, and instead of resting on its lower point was suspended from above by a double cord, or catgut r the twisting of this cord, caused by each vi bration, tended to raise the balance, and its own weight made it descend again, and at the same time turn round in the opposite direction, when the impulse of the first pallet ceased to act on it. The balance was very heavy, as weight was necessary to make it act in the above manner ; and this has caused the mode of its operation to be mistaken by many, who supposed that the cord was merely added to prevent the great friction on the lower end of the arbor, which the weight of the balance would cause.
The introduction of the spiral spring, as a first mover, instead of a weight, took place about the beginning of the sixteenth century. Mr. Peckett, of Old Compton-street, had one of this construc tion, which, from an inscription on it in the Bohemian language, was made by Jacob Lech, of Prague, in . the year 1525.