Afterglows in Spain

Abstract

I HAVE read Mr. Backhouse's note in NATURE (vol. xlvii. p. 582) on the afterglows as seen by him in Spain during February last, and the doubts be expresses on the question whether this phenomenon has always occurred when the sun has been near the horizon. I have observed for many years the setting of the sun in Cadiz on the sea horizon with the purest sky, and never remarked the pink tint, but always the rosy tint in the west and the purple, or Cegensghein, in the east. After the Krakatão eruption, in the clear sky of Madrid, the pink colour of the segment was always more or less visible; and it has been more marked in these later afterglows. The phenomenon is of the same character as that of 1883, but much less brilliant. The apex of the segment rises frequently to 40°.