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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Dip observations by Carnegie Institution
From: Paul Hirose
Date: 2013 May 19, 16:35 -0700
From: Paul Hirose
Date: 2013 May 19, 16:35 -0700
Bowditch (volume 1, 1984) mentions the results of 5000 dip measurements at sea by the Carnegie Institution. I haven't found the source document, but in 1918 a Carnegie scientist, Willliam J. Peters, summarized 3031 dip observations in "Results of Dip-of-Horizon Measurements Made on the Galilee and Carnegie, 1907-1917." [Terrestrial Magnetism and Atmospheric Electricity, volume 23, number 2 (June 1918), page 47] A scan is online at archive.org: http://archive.org/details/journalofgeophys22ameruoft To download (not view online), click "HTPPS" in the "View the book" box. The article begins on page 261 of the document. Peters says the visible horizon was never more than 2.4 minutes above or 2.0 minutes below the geometric horizon. He concludes dip tables that ignore temperature are sufficiently accurate for navigation. --
