114 SEC. 3. MEASUREMENT. 



In an account which he gave Prince Leopoldo de' Medici, Viviani, after 



having described Galileo's experiments on the pendulum, and the way in 



which he applied it to the measurement of time, continues thus : " But as 



ff Galileo was most liberal in communicating his inexhaustible speculations, 



" it frequently happened that the uses and newly discovered properties of 



" his pendulum, spreading little by little, fell into the hands of persons who 



" adopted them for their own ends or inserted them in publications, and 



" by artfully passing in silence over the name of their true author, made 



" such use of them that it was believed at least by those who knew nothing 



" of the origin of the discoveries that the writers were the real authors of 



" them. He next speaks of the observations of the ' Stelle Medicee,' of the 



" tables relating to them prepared by the Padre Renieri, of the offering made 



" by Galileo to the States General of Holland of his method for determining 



" longitudes by means of the eclipses of Jupiter's satellites, and of Galileo's 



" determination to send his son Viucenzo and the aforesaid Padre to Holland, 



" since he himself, being old and blind, was unable to travel thither." He 



then continues : " While, therefore, Padre Renieri was employed on the 



" composition of the tables, Galileo gave himself up to meditations on his 



" time-measurer; and I remember, one day in the year 1641, when I lived 



" near him in the Villa d'Arcetri, that the idea struck him that it would be 



" possible to adapt the pendulum to clocks with weights or springs, and 



" make use of it instead of the usual regulator, hoping that the perfectly 



" equable and natural motion of the pendulum would correct all the defects 



" in the mechanism of the clocks. But as his blindness deprived him of the 



" power of making plans and models of the designs he had formed in his 



" mind, his son Vincenzo having arrived one day at Arcctri, from Florence, 



" Galileo confided his ideas to him, and many times afterwards did they 



" reason over the matter, and at last settled upon the method which is 



" shown in the accompanying draAving, and then set to work' at once 



in order practically to overcome those difficulties which for the most part 



it is impossible to foresee. But Sig. Viucenzo intended to construct the 



instrument with his own hand, in order that by this means the secret 



of the invention should not be reported by the artificers before it had 



been presented to His Serene Highness the Grand Duke, his master, and 



to the States General (to be used for observing the longitude), but he 



put off the execution of his work so frequently that a few months later 



Galileo, the author of all these admirable inventions, fell sick, and on the 



8th of January 1641, ' ab Incarnazione ' according to the Roman style, he 



died ; and consequently Sig. Vincenzo's energies so cooled down that it 



was not until the month of April 1649 that he actually began to make the 



present clock upon the idea explained to him by his father Galileo. He 



then managed to obtain the services of a young man who is yet living 



named Donienico Balestri, a locksmith who had had some experience in 



making large wall clocks, and he made him construct the iron frame, the 



wheels and arbors, but the tooth-cutting and the remainder of the work he 



executed with his own hands, constructing on the highest wheel called the 



scape wheel (tacche) 12 teeth with as many pins (pironi} spaced between 



the teeth, and with a pinion of six leaves on the same arbor, and another 



wheel of 90 teeth which moves the above-mentioned. He then fixed on 



one side of the support which is at right angles to the frame the detent 



(scatfo) which rests on the scape wheel, and on the other side he fixed the 



pendulum, which was made of an iron wire screwed at the lower extremity 



for the attachment of a ball of lead, so that it could be lengthened or 



shortened for regulating. When this much had been done Sig. Vincenzo 



wished me (as one who was in the secret of this invention and who inde i 



had urged him on to complete it) to see, by way of trial, the combine 0. 



