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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Measuring (and Calculating) Dip
From: Andrew T. Young
Date: 2020 Oct 18, 21:24 -0700
From: Andrew T. Young
Date: 2020 Oct 18, 21:24 -0700
References discussion from 2013.
It's surprising that the relation between dip and the inferior mirage isn't more widely known these days, as it was so well appreciated two centuries ago that William Kelly (1832) discussed the relation from his own observations, referring to the earlier discussion by Humboldt. As this was before Bravais introduced the terminology of "inferior" and "superior" mirages, Kelly distinguished the two forms in his notes as "the mirage with shortened or depressed horizon" and "the mirage with elevated horizon."
