NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: sextant calibration
From: Frank Reed CT
Date: 2006 May 14, 13:46 EDT
From: Frank Reed CT
Date: 2006 May 14, 13:46 EDT
" I remember
seeing an ebony octant, from the early 1800s, provided with a
lever-on-lever mechanism for fine-tweaking the angle of the horizon
mirror, for just that purpose. It provided just the right sensitivity
of adjustment, and stayed nicely put when you let it be."
seeing an ebony octant, from the early 1800s, provided with a
lever-on-lever mechanism for fine-tweaking the angle of the horizon
mirror, for just that purpose. It provided just the right sensitivity
of adjustment, and stayed nicely put when you let it be."
Octants from that era were often designed for adjustment to zero and often
there was a large knob on the back of the instrument for this purpose. It was
normal back then. Today it's considered more trouble than it's worth to z-out
the index correction every time.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
