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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robert VanderPol II
Date: 2016 Jan 6, 17:25 -0800
Re: Traditional navigation by slide rule
From: David Pike
Date: 2016 Jan 6, 12:38 -0800
Bob Goethe sent some photos http://fer3.com/arc/m2.aspx/Traditional-navigation-slide-rule-Goethe-jan-2016-g34055
That’s a mighty slide rule Bob. For one who only ever managed to just scrape through in higher Maths, please confirm what all the scales are. Starting from the backside from bottom up my guesses are:
LL2 = e superscript 0.1x
LL3 = e superscript x
C&D = x
C1 = 1/x
C1F = just a guess 1/pi x
CF = just a guess pi x
LL1 = just a guess e superscript 0.01x
L = log base10 x
Front side from bottom up
Sh1 = just a guess sinh-1 some scale on there? Small angles
Sh2 = just a guess sinh-1 some scale on there? Larger angles
Th = just a guess tanh-1 some scale on there?
D = x
S = sin-1 x
ST = sin-1 x or Tan-1 x Very small angles
T = tan-1 x
A&B = x squared
LL00 = very much a guess e superscript 0.000x
LL0 = very much a guess e superscript 0.00x
Many thanks. DaveP
LL2 = This is a LogLog scale used with other LL scales obtaining odd powers of numbers such as 2.37.57 and multiplication of same.
LL3 = ditto
C&D = Single cycle log scales, best precision for multiplying and dividing. Use with A or B to get squares or square roots.
C1 = CI = C scale Inverted so you get 1/x
C1F = CI Folded, see CF
CF = C scale Folded so 1 is in the middle and pi is at the ends making problems with circles easier to work. Also this allows you to use the greater precision of the C scale compared to A or B without going off the end of the scale.
LL1 = ditto
L = This is the natural scale which ironically will give you the log10 of a number when used with C or D. (Ln is the scale to get loge when used with A or B)
Front side from bottom up
Sh1 = Hyperbolic scale of sines. Typically used for electrical engineering functions and for defining the shape of a catenary curve
Sh2 = Ditto
Th = Tangent version of above.
D = Single cycle scale
S = Sines values for angles not near 0 or 90 deg.
ST = Sine and Tangent values for angles near 0
T = Tangents values for most angles
A&B = Double cycle scales that allow you to have results over 10 without going off scale, the cost is reduced precision.
LL00 = Ditto
LL0 = Ditto
http://www.sliderule.ca/scales.htm
