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

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    Re: Traditional navigation by slide rule
    From: Bob Goethe
    Date: 2016 Oct 28, 12:19 -0700

    It seems like most of the items I find when I search for "plano convex plastic lens" are circular.

    >>Try "Bar magnifier" instead. It would find something like this $3 unit which you can scratch a hairline on and cut to right length.<<

    This idea seems to have real merit.  In addition to cheaper, they are typically rectangular, and indeed I should be able to cut one down to size. 

    I can get by The Mall this weekend (if you are from Edmonton, you can hear it in a person's voice when they using uppercase to describe The Mall - which in our context means the West Edmonton Mall; largest mall in the world up until year 2004, and only 3 km from my house) and purchase 2 or 3 different ones of these and try them out for cheap.  Thanks!!

    Bob

       
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