The Sun Position Calculator is a reproduction of a similar
device called a Sundicator that used to be available. It was sold
by Thomas Spencer. I found mine at the swap table at
some years ago. It's the only one I've ever seen.
Thomas Spencer obituary from Harvard Magazine.
THOMAS DICKINSON SPENCER '34, of Pennington, N.J., died March 20, 1995. He was a retired commander in the navy who served as assistant naval attach in Lisbon, Rio de Janeiro, and Paris and naval attache in Greece. Later he became an insurance broker and estate planner. He also toured with the musical Oklahoma in the role of Jud, and was joint holder of a patent for the Sundicator, a navigational instrument modeled after the ancient astrolabe.
The postscript file
Print out the postscript file.
The cursor is meant to be copied onto a transparency.
Cut both sheets into a circle.
Use a thumbtack or something like it to allow the cursor to pivot around the center of the graph.
Set the date and time and read off the altitude and azimuth.
Sundicator manual scan