NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 Mar 27, 20:27 -0400
Hi Alan
Using a slide rule teaches you the magnitude of the answer. You must already have an idea of the order of magnitude of the solution so you know where to put the decimal point.
When designing with a slide rule, you put in safety margins and never ever try to engineer something to within an inch of its life. And, surprise, the Brooklyn Bridge still carries heavy traffic everyday, yet it was designed before the automobile was invented.
The beauty of the slide rule is that precision is related to length. Hence the Bygrave can solve the celestial triangle to an arc-minute. If you want more resolution, just make the scale longer. Bygrave wrapped his scale around a cylinder. So did Otis King and the Fuller by Stanley.
And to think it all started with Napier, but became popular because of navigators(!), using a Gunter's rule.
Sean, Brad and anyone else interested re slide rules, with which I'm NOT especially handy, never having much used them, still:
1. There are whole lot of old buildings, bridges, that sort of things, the design calculations for which were done with slide rules. The above mentioned are still in use.
2. Slide rules will not produce 5 decimal accuracy, assuming that such are desired or needed. Where a couple, perhaps 3 decimal places will serve, slide rules will also, and they are sometimes faster than calculators.
3. With slide rules, if the answer looks really wacky, it likely is.
4. One can scratch their heads with one too, no batteries required.Alan
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