NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Geoffrey Kolbe
Date: 2019 Jun 23, 22:30 -0700
Fred Hebard wrote:
"What does the x do for you?"
Signaling mirrors usually have a small hole in them, if metal, or a hole in the silvering if glass. The idea is that you are trying to reflect the sun at the target using the mirror, but how do you know that you have the mirror at the correct angle?
The way you do this is to look at the target through the hole in the mirror and you will also see a reflection of your face on the other side of the mirror. On your face, you will see a dot of light due to the sun coming through the hole in the mirror.
Now, while looking at the target through the hole in the mirror, adjust the mirror so the image you see of the spot of light on your face is superimposed on the hole in the mirror, and you cannot see the spot of light any more. The sun is now being reflected off the front of the mirror directly at the target.
Geoffrey Kolbe
