Credit: ©The Royal Society
    Image number: RS.16987

    Two figures

    Date
    4 July 1688
    Creator
    Unknown, Artist
    Object type
    Archive reference number
    Manuscript page number
    p130r
    Material
    Dimensions
    height (page): 320mm
    width (page): 210mm
    Subject
    Description
    Two figures on the back of the rough minutes of 4 July 1688, possibly relating to the Fellows' discussions regarding Edmond Halley's equation of time. Halley puts forth a relationship between the diurnal revolutions of the Earth on its axis and the interference of the Moon's motion, also relating this to the motion of pendulum clocks.
    Object history
    4 July 1688: 'Halley read a discourse of his concerning the Equation of Time wherein he shewed the severall forms thereof according to the severall Astronomers, some whereof make the diurnall revolutions in equall times about the Axis, others making them unequall, some on one account, some on another, all which he considered as in a Synopsis, concluding that the inequalities attributed to the Earths revolutions were really in the Moons motion, and the returns of the Meridian to the same fixt starr are precisely equall. In conclusion he showed the effect of this Hypothesis upon pendulum clocks, and how to adjust them so as always to answer to the mean or equall Time' (JBO/8/219).
    Related fellows
    Edmond Halley (1656 - 1742, British) , Astronomer
    Associated place
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          > United Kingdom
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