1911-12.] 
The Fata Morgana. 
175 
XV.— 1 The Fata Morgana. By Professor F. A. Forel, 
Morges, Switzerland. 
Abstract of an Address delivered before the Society on July 11^ 
1911 ; translated by Professor G. G. Knott. 
Among optical phenomena which originate over the surface of water there 
is one so ill-defined and ill-observed as to be still mysterious; till now it 
has received no valid explanation. The Italians call it the Fata Morgana. 
Under conditions still lacking precise description, there appear on the far 
side of the Straits of Messina certain fantastic visions, fortresses and castles 
of unknown cities, which seem to emerge from the sea, soon to vanish again. 
These are the “ palaces” of the “fairy Morgana,” which appear and dis- 
appear at the capricious stroke of the magician’s wand. 
Most of the accounts of the phenomenon are founded on the extravagant 
description and the amazing picture published in 1773 by the Dominican 
friar Don Antonio Minasi, professor of botany at the Roman College of 
Sapienzia. This drawing, with its incoherent groupings of castles and 
boats, reflected and refracted at random in a manner quite inconsistent with 
physical possibilities, was largely the creation of the distorted imagination 
of an artist who did not understand in the least the wonderful illusion. 
To appreciate the confusion which reigns in the scientific world in 
regard to this phenomenon, the reader need only refer to the chapter on the 
Fata Morgana in Pernter’s admirable work on Meteorological O'ptics (Vienna, 
1910). There he will be impressed with the uncertainty of the conclusions 
reached by the author after a study of the insufficient and contradictory 
documents to which he had access. 
Professor V. E. Boccara of Reggio has endeavoured to bring some little 
order into the question,* but with doubtful success, as a critical examina- 
tion of his drawings and diagrams will probably prove. 
In 1854 Charles Dufour rendered a signal service by his recognition of 
the phenomenon of the Fata Morgana on the Lake of Geneva;]* and his 
*“La Fata Morgana,” Mem. della Societa degli spettroscopisti Italiani, xxxi., Catania, 
1902 ; contains a full bibliography of the question, with extracts from the principal 
observations. 
+ “ Mirages et refractions anormales sur le lac Leman,” Bull. Soc. Vaud. Sc. nat., xxxii. 
271, Lausanne, 1853-56. 
