Credit: ©The Royal Society
    Image number: RS.15571

    Diagram for finding apogees, eccentricities and anomalies of planets

    Date
    1670
    Creator
    Unknown, Artist
    Object type
    Archive reference number
    Manuscript page number
    p3a
    Material
    Dimensions
    height (page): 89mm
    width (page): 72mm
    Subject
    Description
    A diagram on a small page attached to Nicholas Mercator's comments on Jean Dominique Cassini's ‘Nouvelle maniere gemoetrique et directe ade trouver les apogées, les Excentricitez, et les anomalies du mouvement des planetes’, Journal des Sçavans (2 September 1669 [N.S.]), 32-35. This is a copy of the diagram on p. 35.

    Urged by Oldenburg (who proposed that Cassini's method might have been first found out in England), Mercator argued at the meeting of the Royal Society on 27 January 1670 that the same method had been demonstrated by Seth Ward in his Examen astronomiae philolaicae (Oxford, 1683). Mercator's paper was published in Philosophical Transactions of the Royal Soceity, vol. 5, no. 57, where this diagram is labelled 'II'. (See the explanation in The Correspondence of Henry Oldenburg, ed. by A. Rupert Hall and Marie Boas Hall, 13 vols (Madison: University of Wisconsin Press; London: Taylor and Francis, 1965-86), VI (1969), 449n2.)

    Mercator's paper and figures appear to have been inserted here among Cassini's letters because they relate to the latter's method, although they do not relate to this particular letter dated 10 June 1669.
    Object history
    At the meeting of the Royal Society on 27 January 1670, ‘Mr. Oldenburg read the paper concerning Cassini’s pretended new method, geometrical and direct, of finding the apogees and excentricities of the motion of the planets: after which he moved, that it might be inquired into, whether the like method had not been already found out in England. Whereupon, Mr. Mercator, having considered this matter in private, produced a paper of his, which shewed, that this very thing was founded upon what Dr. Seth Ward, now lord bishop of Salisbury, had demonstrated in his Astronomia geometrica published in 1656. This paper was read, and being found to be the demonstration of this alledged invention of Cassini, printed as such in the French Journal des Sçavans of September 2, 1669, it was thought proper, that the narrative of the true matter should be published in the Philosophical Transactions, together with the ground, which Mr. Mercator affirmed to have been given long before by Herigon in his Theoria Planetarum; not omitting to make mention of the occasion, that was given to the bishop of Salisbury for finding out that demonstration, viz. by Monsr. Bullialdus, who had acknowledged, that this was wanting in astronomy’ (Birch 2:417).

    Figs II-V, diagrams for 'Some considerations of Mr. Mercator, concerning the geometric and direct method of Signior Cassini for finding the apogees, eccentricities, and anomalies of planets... as was printed in the Journal des Sçavans of September 2, 1669', Phil. Trans. vol. 5, no. 57 (March 1670), pp. 1168-75.
    Related fellows
    Henry Oldenburg (1612 - 1677, German) , Scientific correspondent
    Nicolas Mercator (1614 - 2001, British) , Mathematician
    Jean Dominique Cassini (1625 - 1712, Italian) , Astronomer, Astronomer
    Seth Ward (1617 - 1689, British) , Astronomer
    Associated place
    <The World>
       > Europe
          > United Kingdom
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