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    Re: The voyage of the CWM
    From: Frank Reed CT
    Date: 2003 Dec 23, 16:58 EST
    Jan wrote:
    "Interesting stuff, really."

    Glad you're enjoying it. Does anyone know of any other museums that have digitized old logbooks?

    And you wrote:
    "Frank, when you have logbooks opened, do you realize, how the chronometer and lunar longitudes were used for the following navigator's day work? Was the next reckoning started from them? From the chronometer or from the lunar longitude? (Probably after shifting them to the noon?). Or were they used for obtaining the course to steer at least, as in Norie's Epitome from 1831? Or were they left aside and DR longitude remained the starting point for both the reckoning and for aiming at the point of arrival throughout the all voyage as in the contemporary Bowditch (1851=1838)?"

    It's probably not feasible to guess from the standard logbook entries. However, from the journal of a passenger on a ship in the early 1840s, who took an interest in navigation and even worked lunars himself, it does not appear that the longitude by lunar was used for anything except as a confirmation that the chronometer was (or chronometers were) not grossly in error. Only IF there was a gross discrepancy would you have to start thinking about the actual numbers you're getting from lunars. This same sort of information could be acquired by sighting land and by speaking other ships. The seas were busy back then, and logbooks kept meticulous account of their encounters with other ships. By 1850, with lunars in steep decline, exchanging the longitude with a passing ship was probably the most common form of confirming a chronometer's reading.

    Frank E. Reed
    [X] Mystic, Connecticut
    [ ] Chicago, Illinois
       
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