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Re: 10 inch Slide Rule vs. Pocket Calculator
From: Hewitt Schlereth
Date: 2009 May 27, 22:42 -0400
From: Hewitt Schlereth
Date: 2009 May 27, 22:42 -0400
That's neat, Greg, especially since the cosine part is all at the right end of the scale. I did it with a 10" rule w/o magnifier (under strong light) and got Hc=65�35' , reading right off the rule. -Hewitt On 5/27/09, Greg Rudzinskiwrote: > > The following is a simulated slide rule vs. pocket calculator altitude > sight reduction comparison for declination 20 degrees north, meridian > angle 25 degrees, and latitude 15 degrees north. A 10 inch K & E > 4080-3 was used for slide calculations. A hp 9s scientific calculator > was used for 9 digit comparison. > > Formula: Calculated Altitude = COSdec COSlat COSmeridian angle +/- SIN > dec SIN lat > > The slide rule method uses Bowditch table #31 for inverse SIN. A > magnifying glass x2 was used to improve scale resolution: > (calculation time 3 minutes) > > .822 + .0885 = .9105 inverse SIN .9105 = 65� 35.0' (4.9' low) > > Trig pocket calculator calculation to 9 digits: > (calculation time 90 seconds) > > .822631444 + .088521326 = .911152770 inverse SIN .911152770 = 65� > 39.91' > > Trig pocket calculator to 3 digits: > > .823 + .089 = .912 inverse SIN .912 = 65� 47.0' (7.1' high) > > Preliminary Conclusion: A slide rule with magnifying glass is equal to > 3 digit accuracy if Bowditch table #31 is used for inverse SIN. > > > --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---