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    Re: Cryptic Slide Rule Formulae
    From: Gary LaPook
    Date: 2016 Jan 20, 21:32 +0000
    Formula 1 is the standard sine-cosine formula for Hc.
    Formula 2 is the standard formula for azimuth.
    Somebody else can figure out the other ones.


    From: Jim Rives <NoReply_JimRives@fer3.com>
    To: garylapook@pacbell.net
    Sent: Wednesday, January 20, 2016 1:22 PM
    Subject: [NavList] Cryptic Slide Rule Formulae

    My father-in-law, who sailed for years out of Huntington, LI, passed away a year ago.  In one of his desk drawers I found a 10" Sterlin Slide Rule, No. 584.  It is white plastic, not very eleborate.  (however, still beyond my slide rule skills!)  He had scratched the following 7 formulae on it.  I am just wondering if anyone would recognize the text or method he was using this rule for:  
    In no particular order:  
    1.     sin h = sin L sin d + cos L x cos d cos t
    2.     sin z = cos d sin t sec h
    3.     cos co-d = cos co-h cos co-L + sin co-h sin co-L cos z
    4.    sin t = (sin z sin co-h)/sin co-d
    5.    cos t = tan d cot L
    6.    sin h = sin d csc L
    7     sin A = sin d sec L 
    Thanks in advance for any insight into this.... 
    Darden Rives 

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