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    Re: Altitudes for lunars. was Re: Lunars - Finding Bermuda in 1807
    From: Frank Reed
    Date: 2007 May 22, 11:08 -0400

    George, you wrote:
    " I have an Almanac for 1864, and by then the Almanac was giving (where
    available) the Sun, a planet or two, and 5 or 6 stars, some to East of the
    Moon, some to the West, for the navigator to choose between, or make
    multiple observations.
    I don't know from what date that greater choice was offered. Has anyone
    access to an Almanac from around 1807, to see how many lunar distances were
    tabulated then?"
    Checking 1818 and 1831, it's one star at a time. The change to multiple
    stars happened I believe in 1834, along with many other changes to the
    almanac (or possibly a year earlier since a few changes were rolled out
    before the big revision). In that same year, the lunar distances for the
    planets were added, and the column for "P.L. Diff" was included. Also, the
    distances were thereafter for times in GMT rather than GAT.
    So how do we square this chronology with Basil Hall's account of using
    multiple stars? I think he simply remembered wrong. Memoirs like his
    certainly count as primary source history; he was there, and those things
    did happen. But we always have to remember that the author is reconstructing
    some details. He had detailed journals of his voyages (which he refers to
    occasionally) that formed the basis of his books, but he was writing it all
    out for those books 20 or 30 years later. Similarly, in his account of the
    shipwreck of the Arniston in 1815, he notes that Royal Navy vessels carry
    four or five chronometers. This also may be anachronistic. That is, four or
    five chronometers on a Royal Navy vessel may have been common in 1835 when
    he was writing out the story for one of his books, but in 1815 I would bet
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