A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Dale Lichtblau
Date: 2014 Sep 26, 06:14 -0700
My Lenart Sphere arrived a week or so ago. I first heard about it in a wonderful little book Heavenly Mathematics: The Forgotten Art of Spherical Trigonometry by Glen Van Brummelen. The sphere is a neat transparent "whiteboard" for drawing spherical triangles (etc.), like the navigation triangle. Very useful for visualizing geometry on a sphere.