Credit: ©The Royal Society
    Image number: RS.15989

    Transverse scale for astronomical observation

    Date
    31 December 1673
    Creator
    Henry Oldenburg (1612 - 1677, German) , Scientific correspondent
    After
    John Wallis (1616 - 1703, British) , Mathematician
    Object type
    Archive reference number
    Manuscript page number
    p2
    Material
    Dimensions
    height (page): 286mm
    width (page): 187mm
    Subject
    Description
    Diagram of a transverse scale.

    Johannes Hevelius’s Machina coelestis pars prior (Gdansk: S. Reiniger for J. Hevelius, 1673), included descriptions of the instruments Hevelius used for his astronomical observations. These included open-sighted astronomical instruments using transversal scales. Robert Hooke, in his Animadversions on the first part of the machine Coelestis (London: T. R. for John Martyn, 1674), criticised Hevelius for not using telescopic sights, given the limitations of human eyesight. In this letter dated 31 December 1673, John Wallis offered a mathematical justification for the use of transversal scales, thus siding with Hevelius in the subsequent dispute between Hooke and Hevelius about the appropriate instrument for accurate astronomical observations. This letter is a copy in Henry Oldenburg's hand.

    Copies of this diagram can be found at LBO/6/353 and LBC/6/424.
    Related fellows
    Johannes Hevelius (1611 - 1687, German/Polish) , Astronomer
    Associated place
    <The World>
       > Europe
          > United Kingdom
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