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    Re: Starmaster slide rule on ebay
    From: Peter Monta
    Date: 2019 Nov 28, 15:10 -0800
    Hi Brad,


    ... odd connecting ramps.  

    That is odd; I've never seen one like that.  Either (a) they're going for maximum compactness and want a nearly entire circular outer circumference available for graduations, or (b) it's for ease in laying out the photographic master with rule and compass.  As for accuracy, there should be no impact, since the marks can always be laid out to give the correct central angles.  I guess they could have laid out the approximate skeleton of an Archimedean spiral, filled it in with French curves, and graduated as normal, and they would have been perfectly fine, even without high precision on the spiral.

    Incidentally, speaking of trig rules, quite a while back I happened on a picture of a cylindrical slide rule, of about the same size as an Otis King, graduated for a trig function (probably sin/cos).  Does anyone have a full history of cylindrical trig slide rules (not counting the special-purpose ones such as the Bygrave)?

    Cheers,
    Peter

       
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