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: Gary Harkins
Date: 2004 Oct 11, 21:13 EDT
From: Gary Harkins
Date: 2004 Oct 11, 21:13 EDT
In a message dated 10/11/2004 7:04:52 PM Eastern Standard Time, eremenko@MATH.PURDUE.EDU writes:
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.
As I understand it this only works if the mirror is silvered on the back side. If the mirror is silvered on the front side you need to use cylinders or dominos on edge, etc., to check perpendicularity.
Gary Harkins C400 #140 "Cygnus"
Website http://www.hometown.aol.com/htycgary/myhomepage/index.html
Harbour Towne Marina, Muskegon, Michigan Slip C-28
Harbour Towne Yacht Club, Life Member
C400 National Association
United States Power Squadrons-JN
NRA Life Member
MCRGO (Michigan Coalition for Responsible Gun Owners)
JPFO (Jews for the Preservation of Firearms Ownership)
Website http://www.hometown.aol.com/htycgary/myhomepage/index.html
Harbour Towne Marina, Muskegon, Michigan Slip C-28
Harbour Towne Yacht Club, Life Member
C400 National Association
United States Power Squadrons-JN
NRA Life Member
MCRGO (Michigan Coalition for Responsible Gun Owners)
JPFO (Jews for the Preservation of Firearms Ownership)
