A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2009 Feb 25, 16:53 -0500
This problem does not exist on a “real” Bygrave because the cylinders are stiff and remain concentric with each other. I do recognize the difficulty in getting the scales mounted and keeping them referenced to each other when going through the zig-zag pattern of solution.
I think that local distortions of the one scale to the other will clearly result in errors. Slide rules in general work when the one logarithmic scale is referenced to another logarithmic scale. Distorting one or the other cannot be permitted. NSG21 is absolutely correct.
I remember being the last class to take slide rule instruction in High School. When you use a slide rule today, most people think of it as black magic and have no idea how it works. Further, the electronic calculator leads young engineers to give me as many decimal places as their calculator does, without judgment as to the meaning of those digits. Empty resolution without addition to accuracy.
I haven't seen the problem you mentioned. I sealed the
Cotangent scale in normal plastic protection sheets (about one buck each at
Fryes) used for protecting documents which are quite rigid. I will experiment
with bending the scale and working a sample problem and get back to you.
I would like to share some experience in using this (transparency over printed)
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