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    Re: Bygrave position line slide rule
    From: Zvi Doron
    Date: 2004 Mar 18, 22:14 -0000

    Hello,
    
    Based on the information and images Mr. Koberer kindly sent me and on some
    details and a drawing from Weems' book Air Navigation I have now built a
    fully working model of the Bygrave position line slide rule. It is 2-3 times
    larger than the original and is quite accurate, giving calculated positions
    to within about 1' of arc (1 nautical mile) with the inputs being Dec, Lat
    and LHA, so in effect it replaces the normal sight reduction tables. It took
    some 8 hours of work to make. Do contact me if you are interested in
    details.
    
    Kind regards
    
    Zvi
    
    ----- Original Message -----
    From: Zvi Doron 
    To: 
    Sent: 28 February 2004 16:01
    Subject: Bygrave position line slide rule
    
    
    > Hello,
    > Henry Hughes & Son of London, England used to make a cylindrical 3 part
    > position line slide rule for astro navigationsometims called "Bygrave"
    that
    > worked on the principal of solving two right angle triangels instea of the
    > complete PZX in one calculation. Francis Chichester used one on his epic
    > solo flight across the Tasman Sea (1931) and Weems in his book "Air
    > Navigation - British Empire Edition" gives a drawing and a few details. I
    > could not find any reference to it on the web.
    > Has anyone - ever used one? got one? seen one? knows if they can be had
    and
    > for how much? Any information will be gratefuly received.
    > Thanks
    > Zvi
    
    
    

       
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