Posted by Jerry Crouch on September 12, 2003 at 00:25:57 from 63.190.232.77 user Jerry.
In Reply to: Compass (and War) posted by Robert Dilley on September 11, 2003 at 17:32:07:
I am rather ignorant about compasses, navigation, and the like. What is a prismatic compass and how does it differ the compass that presumably the Swallows had for their survey? And why it that you cannot place it on the ground to steady it while taking a bearing? Is it because a prismatic compass has a sighting device, which of course could not function at ground level I have sometimes seen compasses designated as lensatic compasses. These seem to have a peep sight on one side and a cover with a thin slit to sight through on the other.