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    Re: Lunar eclipses and other things
    From: Alexandre Eremenko
    Date: 2004 Oct 27, 01:17 -0500

    Lisa:
    
    On Wed, 27 Oct 2004, Lisa Fiene wrote:
    
    > This is so interesting.
    > Shall have to read the thread on Wulf's grid.
    
    The thread on Wulff's grid is small and easy to read:
    it consists of two messages:-)
    
    The Star Globe btw is a "modern" version of the armillary sphere
    of Erathosphenes.
    
    Experienced people somehow convinced me that the usual
    analog computing devices (I knew the Grid and the Star Globe
    at that time, now I can add the planispheric astrolabe)
    are useless in Cel Nav, so I decided not to continue this threas:-)
    (They are indeed useless in the sense that they do not give
    you good precision. 1/2 of a degree in the best case).
    
    In modern times, there were attempts, using advanced
    technology, to build analog devices which permit you to reduce
    a sight with sufficient precision.
    Sort of astrolabia/star/globe but with 1' or maybe even better
    precision. So that instead of using the reduction tables,
    you could just move some skrews and obtain the answer.
    One of these devices is shown on p. 86 of
    "The book of sextant" by A. J. Hughes.
    It is called Hagner Position Finder.
    I would love to have one of such things in working condition:-)
    
    Probably it was terribly expensive.
    
    But invention of computers arrested all this development...
    So now we live in the world of plastic, batteries and
    electronics...
    
    The Star Globe btw is a "modern" version of the armillary sphere
    of Erathosphenes.
    
    > Following is a quote from DON QUIJOTE OF LA MANCHA, which I love....
    
    Me too:-) I even have a collection of beautiful illustrated editions
    of this book, but...this is definitely out-of-the list topic:-)
    
    Alex.
    
    
    

       
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