Study of a lighting effect observed in the southern Atlantic Ocean, 2 December 1884, caused by atmospheric dust and gases ejected by the 1883 volcanic eruption on the island of Krakatoa (Krakatau, Indonesia). Plate 1 from the book Untersuchungen uber Dämmerungserscheinungen zur Erklarung der nach dem Krakatau-ausbruch beobachteten atmospharisch-optischen Storung, by J. Kiessling (Hamburg, Leopold Voss, 1888). The plate is inscribed above: ‘Kiessling, Dämmerung-Untersuchungen. Taf. I.’ Inscribed below: ‘PURPURLICHT IN REGELMASSIGER ENTWICKLUNG (ABEND.) [Purple light in regular development] Pechuel-Loesche. Südatlantische Ocean (28.5 S. 4. O.) Dez. 2, 1884. Chromolithographie von Leo Kempner & Co. in Hamburg. Verlag von Leopold Voss in Hamburg (und Leipzig).’ Karl Johann Kiessling (1839-1905) German physicist, replicated twilight glow phenomena in the laboratory. Eduard Moritz Pechuël-Loesche (1840-1913) German naturalist and watercolour painter who travelled widely, including on expeditions to the Congo, Africa.