NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextants, vernier and micrometer.
From: George Huxtable
Date: 2006 Oct 31, 10:13 -0000
From: George Huxtable
Date: 2006 Oct 31, 10:13 -0000
About the sextant arc that Alex pictured at http://www.math.purdue.edu/~eremenko/pic1.jpg Henry Halboth wrote- | It looks to me to be a 10 second vernier. Most older sextants/octants had | either 10 or 15 second reading verniers. But I think Henry should look again. It has 5 divisions to each minute of the Vernier arc, as I see it, which means that it measures to 12 seconds, or 0.2 arc-minutes, somewhere between the two values that Henry suggested, of either 10 or 15 seconds. That has advantages when the arithmetic started to be done in decimals of a minute, rather than in seconds. Perhaps it dates the instrument to the later days of Vernier sextants. George. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
