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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Accuracy: main shades vs eyepiece shades?
From: Geoffrey Kolbe
Date: 2019 Jul 27, 03:13 -0700
From: Geoffrey Kolbe
Date: 2019 Jul 27, 03:13 -0700
Brad Morris said:
"I selected ~ 1900 as a date by which nearly all sextants were made using float glass. Its probably earlier."
"Float glass" - where glass solidifies on the surface of a bath of molten tin, and so is optically flat top and bottom without further polishing - was developed by Pilkington Brothers in the mid 1950s.
Geoffrey Kolbe
