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Re: Selection of slide rules, compendium of messages
From: Gary LaPook
Date: 2011 Nov 25, 23:49 -0800
From: Gary LaPook
Date: 2011 Nov 25, 23:49 -0800
Paul Hirose worked out a sample problem using the Bygrave method on a 10 inch slide rule, using latitude 34° N, dec. 20° N and LHA 14°, see: http://www.fer3.com/arc/m2.aspx?i=108411&y=200905 I decided to do the same sample problem on several slide rules. I also worked it out using a calculator so I know that the correct answer for Hc = 71° 17.4'. Paul got 71° 17' a difference of 0.4'. Using a cheep Sterling plastic slide rule the Hc = 71° 18', difference of 0.6'. Using a K&E 4081-3 I got 71° 18', difference 0.6'. Using a K&E 4080-3 I got 71° 17', difference 0.4'. Using a Pickett N803-ES I got 71° 20', difference 2.6'. Using my Bygrave cylindrical replica I got 71° 18', difference 0.6'. Using my flat Bygrave I got 71° 18', difference 0.6'. So using a ten inch slide rule with the Bygrave method produces quite usable results but the two Bygraves produce better consistent accuracy. A computer simulation confirms this, see: http://www.fer3.com/arc/m2.aspx?i=108985&y=200907 gl --- On Thu, 11/24/11, Gary LaPook <garylapook@pacbell.net> wrote:
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