A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Hanno Ix
Date: 2014 Jun 19, 07:54 -0700
nice tutorial of PS in it's own right.
To be clear; in the flat Bygrave, the cosine scale is printed on transparent material and laid over the cotangent scale.
My Postscript code at http://fer3.com/arc/m2.aspx/Postscript-code-for-making-Bygrave-Scales-Stuart-mar-2014-g27398 is very flexible and it would be straightforward to produce 2 copies of the cosine scale on a single page. The variable CosScaleStartPosition controls the position of the cosine scale on the page. Your result could be achieved by generating 2 versions of the file BygraveAltFlat.prl and passing the cosine scale through the printer twice. The 2 cosine scales would not necessarily precisely align. I'm not sure I completely understand your explanation of how you plan to use it so it's not clear to me whether that would be a problem.
As I said my code is pretty flexible and contains features that you might find useful. There is a switch that causes the cosine scale tick marks to be drawn pointing downwards which might improve clarity when reading the scales.
It is also possible to have a cosine scale that runs from say -89°10' through zero to +89°10' rather than 0° to +89°10' as it does now. That way the division cot(z) = cot(x) / cos(y) can be achieved by aligning the zero pointer on the cosine scale with x on the cotangent scale and then finding y by moving right to left along the cosine scale and reading z off the cotangent scale. I will post an example with both features switched on to demonstrate these,