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Hello, 

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