# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

**Re: Traditional navigation by slide rule**

**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 2.3^{7.57 }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 log_{10} of a number when used with C or D. (Ln is the scale to get log_{e} 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