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    Re: Scrap paper with time sights c.1870
    From: Henry Halboth
    Date: 2013 Feb 22, 23:29 -0500
    Hi Lars,

    Great work. Thanks a million for the effort.

    Your fit, at least for for December 24, 1870, appears to be right on the money. Unfortunately, I just do not have the time to go into this in detail at the present, but can if you wish forward a copy of the American Nautical Almanac for the year 1870, or for any other year, to further your work.

    Thanks again.

    Henry

    On Fri, Feb 22, 2013 at 3:04 PM, Lars Bergman <lars.h.bergman@gmail.com> wrote:

    Brad wrote: "It matters not what the actual Equation of Time was. It matters only in the volume of Bowditch that the scrap of paper was found in! I think it highly likely that our navigator got his EoT value from a table found within."

    I agree, it is not unlikely that the navigator got his ephemeris from some "simplified" almanac, e.g. Bowditch. I have Bowditch 20th edition, 1851, giving data "for the year 1848, which will answer nearly for the years 1852, 1856, 1860" and for three more years after these; for 1851 ("or nearly for 1855, 1859, 1863") EoT is stated as 1m11s and declination 23d21m for Dec 27th.

    Attached is an excel file giving a summary of the 20 observations reduced, starting December 24th and ending January 9th. It is possible to "run" these data against an almanac for different years and find out the year that gives the smallest residual error.

    In Frank's picture there are 10 observations per page, the first 5 are on the left page, right column, top down, obs 6 to 10 in the left column. Obs 11 to 15 are on the right page, left column, top down, and obs 16 to 20 in the right column, top down.

    The vessel was eastbound, into the Mediterranean. During the period a net distance of some 2300 miles was covered in 16 days, giving an average speed of 6.0 knots. The chronometer was gaining 5 seconds a day.

    There may be typing or interpretation errors ...

    Lars 59N 18E


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    Attached File: 122462.summary-c1870.xlsx

    View and reply to this message: http://fer3.com/arc/m2.aspx?i=122462


       
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