Twilight.
Riggenbach, Albert. **B.2008.57
Beobachtungen uber die Dammerung insbesondere tiber das Purpurlicht und seine Beziehungen zum Bishop*schen Sonnenring. Habilitationsschrift. Basel. He George 1886. 105 pp. 89. "Bishop's ring" is named after Sereno E. Bishop and is an atmospheric or meteorological phenomenon, first observed after the eruption, on Aug. 26. 1883, of the volcano Béntinhed} Jave. The appearance