NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Perpendicularity again. was: Adjusting Central Mirror
From: Jim Thompson
Date: 2004 Oct 11, 20:39 -0300
From: Jim Thompson
Date: 2004 Oct 11, 20:39 -0300
Isn't that what twin cylinders are for? I assume that by lining up their tops as they sit on the index arm, the eye is forced into the correct angle. I use the ones Celestaire sells: http://www.celestaire.com/catalog/products/1903.html Jim Thompson jim2@jimthompson.net www.jimthompson.net Outgoing mail scanned by Norton Antivirus ----------------------------------------- > -----Original Message----- > From: Navigation Mailing List on Behalf Of Alexandre > Eremenko > The question was: how do you properly CHECK perpendicularity > of the index mirror to the sextant frame. > There are several versions of this check. > The simplest one and most common one says: > look into your index mirror so that you see a part of the arc > directly > and another part of the same arc reflected in the mirror. > If everything is OK, you see the arc as a straight continuation > of its reflected image. > But whether this is so or not, DEPENDS on the angle of your > sight > with respect to the plane of the sextant frame! > I just cannot believe that nobody has noticed this.
