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    Re: Star-star distances for arc error
    From: Gary LaPook
    Date: 2009 Jun 29, 10:41 -0700

    
    I tried the same thing, printing the cosine/secant scale on transparency 
    and wrapping it around the other scale and had the same problem, keeping 
    the two scales separate. I then modified the cosine scale to print in 
    red which is a great improvement. That's when I got the idea to make the 
    flat model. You can download the scales from the archive at :
    
    
    
    http://www.fer3.com/arc/img/107473.lapook2.pdf
    
    http://www.fer3.com/arc/img/107473.lapook1.pdf
    
    http://www.fer3.com/arc/img/108719.revised%20form%206-18-09.pdf
    
    You can also adjust the size of the printouts so as to make them the 
    right size to wrap around a tube and make a recreation of a tubular 
    Bygrave. You can make the cursor by simply printing a line on a 
    transparency and wrapping it around the other two scales. Give the flat 
    model a try.
    
    gl
    
    
    
    
    douglas.denny{at}btopenworld.com wrote:
    > I should have also commented:
    >
    > I would dearly like to get my hands on a real Bygrave slide rule or the 
    German equivalent to play with and try it 'for real'; (hands covered in white 
    gloves to preserve it of course).
    >
    > I have only seen one example and that was in the Aviation museuum in Hendon. 
    It looked in poor condition too.
    >
    > >From a programme supplied by Dr. Kolbe I made one with a cardboard tube and 
    a sliding clear outer ("cos") scale just to try the operations for the fun of 
    it.  It proves the principle but is near impossible to use as the two scales 
    become so confusing one on top of the other.
    >
    > I have not yet tried using different colours for the different scales to see 
    if it is then possible to use it more successfully.  
    > Interesting to speculate if Mr. Bygrave tried this and rejected it as being 
    impracticable, reverting to the separated scales of a conventional 
    cylindrical slide rule and movable cursor to reduce confusion possibilities.  
    Probably not.
    >
    > What I do wonder is what happened to all these Bygrave slide rules - and the 
    German ones?  There must have been hundreds made and yet now they are 
    incredibly rare it seems.  The Air Ministry must have had boxes full of them 
    somehwere on the shelves of some nondescript warehouse in teh middle of 
    nowhere.  It is nice to contemplate that perhaps they are still there? ... 
    >
    > ...though much more likely thrown out by some idiot who was following orders 
    to throw away "that rubbish over there on the shelves released from the Air 
    Ministry inventory as uselss and obsolete!  
    >
    > Vandals!
    >
    > Douglas Denny.
    > Chichester.  England.
    >
    >
    > Douglas Denny.
    > Chichester.  England.
    >
    >
    > >
    >
    >   
    
    
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