A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2021 May 3, 03:48 -0700
I’ve been thinking about this myself for quite a while but never got round to it. I reckon the first thing you need to do is make the globe perfectly spherical by cutting the top mounting flush and filling in with plastic putty of some sort. Then you need a cradle made from stiff card. You’ll need to make a flat top with a circular hole in it the same diameter of the sphere. You’ll need to make two such pieces and cut one across the centre to make two base pieces which you can notch to interlock.
First mark the centre of the top piece. From the centre draw out 12 radials 30 degrees apart. Then draw the circle with compasses and cut it out. Glue the top to the base pieces and sit the globe in the cradle. Using a spirit-based pen, draw in the equator, and using the 12 radials, make witness marks to indicate where the 30-degree meridians will be. Spin the globe in the cradle until the equator is vertical and dot in the North and South Poles from the 12 markings on the top of the cradle. To get the most accurate position for the Poles, you might have to do this in pencil with three lines at say the 0EW, 120W, and 120E positions and dot in the Poles at the centres of the triangles produced. Then spin the sphere about its Poles and mark in the meridians with spirit-based pen using the witness marks you drew around the equator to line the sphere up un the cradle. You just have to draw round the top piece to mark in the meridians.
Next, and this is probably the trickiest bit, so practise with pencil first, spin the globe about its poles in the cradle holding the pencil against 30 and 60 N & S on the top-piece to draw in the parallels of latitude. Use a similar technique to mark in the ecliptic and the stars. Please let me know how you get on. DaveP