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    Reply about google earth plot of Bowditch voyage
    From: George Brandenburg
    Date: 2011 Jul 20, 16:17 -0700

    >From: george---com
    >Date: 19 Jul 2011 06:47
    >
    >George B,
    >
    >I have a question about your "Bowditch_FInal_Voyage.kmz" google earth plot. Was Bowditch's intent to >navigate toward the intersections of Lat & Long? His plotted course seems to show that.
    >
    >George


    Hello George,

    I see you were perusing Bowditch Lectures folder at my website (http://public.me.com/gwbburg). Did you also have a chance to browse the slides? The Google Earth file (.kmz) taken from the logbook of his final voyage was quite a hit. (If anyone would like to see this without running Google Earth, I have also posted a movie (.mov) file of the of the animation.)

    I'm not sure what you mean by navigating to lat & long intersections. But some explanation of the file is probably a good idea. The points are daily positions taken from his logbook stored at the Peabody Essex Museum's Phillips Library. The color code is brown for days with obscured sun, yellow for days with noontime solar lat measurements, red for days when he was able to do a lunar-solar long measurement, and green when he did a lunar-stellar long measurement.

    The yearlong voyage destination was the Pepper Islands off Indonesia, with a return stop at Isle de France. One thing that is immediately notable from the voyage plot is Bowditch's love of lunars. He was the captain on this voyage, but had little interest in the running of the ship. He apparently spent most of his time reading when he wasn't doing cel nav. He was studying and translating La Place’s Mécanique Céleste, a project that he eventually considered to be his most important scientific endeavor. But his favorite pastime seems to have been lunars whenever possible!

    Other obvious features of the voyage are the closely spaced points in the "doldrums" at the equator, the course of more or less constant latitude to clear the Cape of Good Hope, and the much more direct routing possible on the return voyage. I have also plotted the early voyages of the ship Friendship, which you can find in movie format at my website, and the similarity is remarkable between Bowditch's final voyage and the Friendship's maiden voyage, both from Salem to Indonesia (except for the frequency of lunars!).

    The ending of Bowditch's voyage, when he sailed into Salem Harbor on Christmas Eve after several days of impaired visibility, is another great story. The legend is that he miraculously pointed into the darkness and brought the ship home. Having studied the logbooks I think that he did exactly what he should have done as a very competent navigator. He had one lunar and several sun sights in the final week, and these coupled with numerous soundings on George's Bank and an encounter with an outbound ship gave him all the information he needed to turn into port. A final sighting of a familiar light and he was home. (If you run the Google Earth file his logbook entries for the final week can be displayed by clicking on the points.)

    So I didn't really answer your question, but I hope I clarified a few things.

    Best regards,
    George B

    p.s. You signed your message George without a last initial. George H was a revered member of this list who hasn't been heard from since April, but I've always added "B" to my name to avoid confusion. -GB

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