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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Dip observations by Carnegie Institution
From: Paul Hirose
Date: 2013 May 19, 22:03 -0700
From: Paul Hirose
Date: 2013 May 19, 22:03 -0700
I wrote: > Peters says the visible horizon was never more than 2.4 minutes above or > 2.0 minutes below the geometric horizon. Since he put the sentence in all italics, it must have been one of the main points of the article, and so I should have quoted it directly: "In all the observations taken first on the Galilee, then continued on the Carnegie, amounting to 3,031 determinations, the refraction has not raised the horizon more than 2.4′ nor depressed it more than 2.0′ below the position in which it would be seen if no refraction existed." Most observations were at height of eye 5.5 or 7.3 meters. Dip would have been 4.1' or 4.8' by the traditional formula, and about .4' greater in the absence of refraction. --
