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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: The Bygrave
From: Hanno Ix
Date: 2009 Jul 26, 14:37 -0700
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From: Hanno Ix
Date: 2009 Jul 26, 14:37 -0700
| Dear waldendand: I have a technical question here: When you designed this scale, what exactly was the diameter of the drum and the thickness of the paper? Did you perhaps make any experiments as to what paper length fits exactly around the drum after it has been bend to a cylinder? I see things this way: To fit precisely, the cylinder formed by the paper needs to have an inner diameter equal to the outside diameter of the drum. So, because of the thickness of the paper, the outside of the paper cylinder must be bigger yet. As you bent the paper it will be deformed somewhat, and the cylinder's inside/outside diameters will probably be different from the original paper length divided by pi. Since the scale is printed on the outside this would impact the accuracy of the scale. This error need not be big to cause errors of a min or more. It seems difficult to predict the deformation of the paper, given the complexity of its matrix. So I wonder, Is there anyone that has observed such an effect in the practical world? If it was not negligible, how did you deal with it? Similar questions apply, of course, to the next scale (cosine) and perhaps a third (cursor). If I were to make just a single Bygrave, I'd just turn the drum and/or play with the scale plotting routine until things fit. However, if we are perhaps talking about making a number of Bygraves we would need a more predictable solution. Regards --- On Wed, 7/22/09, waldendand@YAHOO.COM <waldendand@YAHOO.COM> wrote:
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