Curious Shadow Effects

Abstract

IT is obvious that the bow seen by Mr. Warner and described in NATURE of January 28 (p. 296) was the “Ulloa's ring,” the “Nebelbild” or “Brockengespenst” of the Germans, fully explained by Fraunhofer. The oval form is a necessary consequence of our seeing the sky as a depressed vault or segment of a hollow. sphere, as I have demonstrated it in my “Meteorologische Optik,” I. Abschnitt, p. 29 ff.; see especially p. 33, Fig 5.