This opinion is strongly corroborated by the observations of Hamberger in Beckmann's History of Inventions. o These horologia," he remarks, " not only pointed out the hours by an index. but emitted also a sound. This we learn from Primaria Instituta Canonicorum Pnenzonstaten tiunz, where it is ordered that the sacristan should regulate the horologium, and make it sound before matins to awa ken him. I dare not, however, venture thence to infer. that these machines announced the number of the hour by their sound, as they seem only to have given an alarm at the time of getting up from bed. 1 have indeed never yet found a passage where it is mentioned that the number of the hour was expressed by them ; and when we read of their emitting a sound, we are to understand, that it was for the purpose of awakening the sac, istan to prayers. The ex pression horologiunz cecidit, which occurs frequently in tie before-quoted writes, I consider as allusive to this sound ing of the machihe. Du Fresne, in nay opinion, under the word Horologium, conceives wrong the expression de pon deribus in imam delallsis, because the machine was then at rest, and could raise neither the sacristan or any one ease, whose business it was to beat the scilla." When an alarm is set off, the weight, which is the mov ing force of it, very soon falls to the bottom, and then the alarm ceases.
In attempting to make the first 'scapement, there can be little doubt that something of the circular or cylindrical kind was contrived, and the only thing which could give it an alternate motion, was either a spiral spring or a pendu lum ; but these things being then unknown, the clockmaker was obliged to seek after other methods, and at last pro duced the crown wheel and verge 'scapement. How came it that means so complicated were fallen on, when those which were more simple and better were over-looked ? It is a very singular circumstance, that a small ball or weight, when suspended by a slender thread, and drawn a little aside from the perpendicular, on being let go, conti nues to vibrate for a considerable time, and with the utmost regularity. Many things in domestic life were hung up or suspended by strings, and were every day seen or ob served ; yet what a long time elapsed before any thing of this kind was ever thought of, or applied to regulate the motion of a clock It is said that Galileo took his idea of a pendulum from the motion of a lamp, suspended from the roof or ceiling of a church, which had been acciden tally set a vibrating. He used the simple pendulum in his astronomical observations, long before it was applied to a clock. Some of the earlier astronomers, as well as Gali leo, used a common string and hall, which they made to vi brate a little while, doting the time of an observation of any of the heavenly bodies. Yet even these astronomers did not think of its application to clocks. Some watch finishers, when their watch is finished, for want of a pen dulum clock, regulate it by means of a ball and string, which will answer very well, by taking 50 vibrations of a pendulum's length for seconds, in the same time that the wheel ought to make one revolution.
As gravitation is the principle on which the pendulum is founded, it cannot properly be considered as an invention, as sonic have called it, whatever name may be given to it when applied to regulate the motion of a clock. The pendu lum having before this been long known in its simple state, and used as a sort of time measurer, it was no wonder that the idea of applying it to a clock was entertained by seve ral persons nearly about the same period. The movement of the old balance clocks was not adapted for the applica tion of the pendulum, so as to give motion to it ; the wheels in it were all flat ones except the crown wheel, and no other 'scapement at this time was known but that of the crown wheel and verge ; so that, without considerable dif ficulty and invention, the pendulum could not well be ap plied to this construction of a clock movement. The pocket watch had been made a considerable time before this, and the construction of its movement, which had a con tratc wheel in it, would naturally lead them to that of one which would adapt itself to the motion of a pendulum, as by means of the emirate wheel the crown wheel could be made to stand in a vertical position ; where as, in the old balance clocks, the position was horizontal. Galileo seems early to have discovered the properties of the pendulum, and the investigation was prosecuted with great success by Huygens. The son of Galileo applied the pendulum to a clock at Venice in the year 1649 ; but to what sort of a movement we cannot pretend to say, though we suspect, from that want of success which seems to have attended his trials, that he had not adopted the con trate wheel movement, already mentioned, as the most pro per for it. We know that Huygens made use of this sort of movement, as the only one fit to be regulated by the mo tion of the penoulum, which he had also applied. Of late, another candidate for the application of the pendulum to a clock has been brought forward by such respectable autho rity, that leaves little or no room to doubt of its authenticity.
Grignion informs us, 44 that a clock was made in 1642, by Richard Harris of London, for the Church of St Paul's, Covent Garden, and that this clock had a pendulum to it." It appears, from unquestionable evidence, that Galileo, mathematician to the Grand Duke of Tuscany, first dis 'covered the properties of the pendulum, used it in his as tronomical observations, and wrote a tract explaining the principles of it. This tract was translated from the Italian into French at Paris, printed hi 1639 in a duodecimo volume, and sold by Pierre Ricolet. He intended to apply it to a clock, but this he never put into execution. Father Al exander says, that they had nothing better than the ba lance clocks in France until the year 1660." The application of the pendulum to a clock, and of the spiral form of a pendulum spring to the balance of a watch, the greatest improvements that could possibly have been made in the machinery of time measuring, and they both happened to take place nearly about the same period.