spherograph
noun
sphero·graph
| \ ˈsfirəˌgraf, -fer-, -grȧf\
Definition of spherograph
1
: two cardboards used especially in navigation and astronomy, containing various circles, and turning upon each other in such a manner that any possible spherical triangle may be readily found and the measure of the parts read off by inspection
2
: a disk ruled with meridians and parallels in stereographic projection for the solution of problems in spherics
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