File:Galileo, his life and work (1903) (14579915200).jpg

Identifier: galileohislifewo00fahi (find matches)
Title: Galileo, his life and work
Year: 1903 (1900s)
Authors: Fahie, J. J. (John Joseph), 1846-1934
Subjects: Galilei, Galileo, 1564-1642 Astronomy Astronomers
Publisher: London, J. Murray
Contributing Library: Wellesley College Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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oor three palms (the greater it is the less trouble inattending it). This sector I make thickest in themiddle radius, tapering gradually towards the edges,where I terminate it in a tolerably sharp line, toobviate as much as possible the resistance of theair, which is the sole cause of its retardation. Thissector is pierced in the centre, through which ispassed an iron bar shaped like those on whichsteelyards hang, terminated below in an angle, andplaced on two bronze supports. If the sector (whenaccurately balanced) be removed several degreesfrom the perpendicular, it will continue a to-and-fromotion through a very great number of vibra-tions before coming to rest ; and in order thatit may continue its oscillations as long as it iswanted, the attendant must occasionally give ita smart push so as to carry it back to largeoscillations. Now to save the fatigue of continually countingthe oscillations, this is a convenient contrivance—asmall delicate needle extends from the middle of the
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GALILEOS DESIGN OF A PENDULUM CLOCK (see next page). From Favaros Galileo e Cristiano Huygens. Nuovi documentisuir applicazione del pendolo all orologio (Nuovi siudiCalileiani, Venice, 1891). 398 GALILEO AT ARCETRI (1636- sector which in passing strikes a rod hung at oneend. The lower end of this rod rests on the teethof a horizontal wheel as light as paper. The teethare cut like those of a saw. The rod strikingagainst the perpendicular side of a tooth moves it,but when returning it slips over the oblique side ofthe next tooth and falls at its foot, so that themotion of the wheel will be in one direction only.By counting the teeth you may see at will thenumber passed, and, consequently, the number ofoscillations or periods of time which you wish tomeasure. You may also fit to the axis of the wheela second, with a smaller number of teeth and ingear with a third wheel having a greater number ofteeth, and so on. As the error of clocks consistschiefly in the inability of mechanicians to a

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