Dear All,
As proven in a separate tread on "Sun elevation tool/ horizontoscope",
stereographic projection is
a fascinating geometric construction with great potential in gnomonics.
During last year I explored the idea of vertical stereographic sundial and it
resulted in
a paper describing
Dear John,
I know this object as “Horizontoscope".
http://www.horizontoscop.com/eng/index_eng.html
I bought one recently after reading about it in one of Helmut Sonderegger’s
articles, where he gives the math of it.
There is a description of the TNO "jellyfish", as it was affectionally
known, in a paper by J van der Eijk, "Instrumentation for Solar Studies",
in the *Proceedings of the CIE Intersessional Conference on Sunlight in
Buildings*, Bouwcentrum International, Rotterdam 1967, and reprinted as
