NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Angles without a protractor
From: John Huth
Date: 2012 Oct 13, 09:06 -0400
From: John Huth
Date: 2012 Oct 13, 09:06 -0400
This is not quite the same thing, but I made a quadrant by successively bisecting angles using the method one learns in geometry classes. At a certain point, I used a ruler to bisect the chords and project back onto the arc. I ended up with 64 increments over 90 degrees. I then made a kind of 'vernier' by projecting triangles to the midpoint of each angle.
When the plumb line hangs down, I not only measure the increment, but also interpolate using the triangle. I guessed that I had an uncertainty of about 20 arc-minutes. I actually have to dig in and measure this, and get a genuine distribution of how far off I am.
On Fri, Oct 12, 2012 at 9:53 PM, Sean C <yhshuh@aol.com> wrote:
"...curve giving the correction to be applied to your calculated angle."
-Robert BerneckyI tried drawing two random angles (52° and 80°) using your graph and they were spot on. Thanks, again!
And Lu, Re your suggestion about 6"...good idea.
Cheers,
Sean
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