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    Re: When did "time sights" fade away?
    From: Henry Halboth
    Date: 2011 Jul 20, 19:06 -0700

    Thank you for your kind response to my posting on the subject.

    I otherwise have reference to your posting of 26 Oct 2007, responding to Gary LaPook's earlier comments on the Time Sight, together with attachment, as noted in your post.

    I certainly agree that a Sumner line as originally produced by connecting two positions calculated by Time Sight is a chord of the circle of equal altitudes, and thus, particularly at high altitudes, may differ from the tangent LOP produced by the intercept, or Marc St. Hilaire method. However, the tangent produced by employing by a single Time Sight position and an LOP perpendicular to the azimuth, for all practical purposes, is identical to the intercept tangent produced by Marc St. Hillaire.

    I have not independently verified the foregoing, however, can cite references claiming close coincidence between the Time Sight and Marc St. Hilaire tangents, with resultant positions developed by use of conventional logarithmic tables agreeing to within 0.5 nautical miles.



    --- On Tue, 7/19/11, Andres Ruiz <navigationalalgorithms@gmail.com> wrote:

    From: Andres Ruiz <navigationalalgorithms@gmail.com>
    Subject: [NavList] Re: When did "time sights" fade away?
    To: NavList@fer3.com
    Date: Tuesday, July 19, 2011, 1:55 AM

    Thanks to Henry for his summary.
    And to gl for the references.

    Also Borda and Johnsonn proposed a variation of LoPs but do not became so popular as Sumner and St Hilaire's.
    see the the attached PDF in http://fer3.com/arc/m2.aspx?i=103619&y=200710

    Andrés Ruiz
    Navigational Algorithms
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