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    The Bygrave Slide rule
    From: UNK
    Date: 2009 May 29, 14:39 -0700

    It's just been drawn to my attention that in the book "Spherical Trigonometry" 
    by J.H. Clough-Smith, on page 105, "Aquino's log tangent + log secant method" 
    is described. It seems fairly clear that the Bygrave Slide Rule is based on 
    this method, which talks about 'only needing tables of log secants and log 
    tangents'.
    
    I rest my case.  Bygrave must have consciously changed the name 'secant' to 
    'cosine' in his written descriptions.
    
    I have a .gif of this description but as a non-member I can't post it here.
    
    Peter Martinez
     
    --------------------------------------------------------
    [Sent from archive by: peter.martinez-AT-btinternet.com]
    
    
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