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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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