Tables for azimuths, great-circle sailing, and reduction to the meridian, with a new and improved "Sumner" method: latitudes 85° N. to 85° S., declinations 85° N. to 85° S : also other useful navigational tables, with numerous examples of double altitudes, equal altitudes, azimuths, etc.
Blackburne H. S | Marcus F. Marks government printer | 1916