LUMINOUS SHOWERS. 147 



enveloped in a dense fog of a most remarkable nature. It 

 was termed "dry," as even at night no dampness was ob- 

 served. It was first seen at Copenhagen, its coming being 

 heralded by severe storms. A few weeks later it appeared 

 in various parts of France, and rapidly seemed to spread 

 over Europe and portions of Asia. During the day it had 

 a metallic glow, which at night changed to a phosphorescent 

 light, so brilliant that ordinary print could be read by it. 

 Many attempts to explain it were made by the savants of 

 the day, and it was universally supposed to be due to the 

 earthquakes and volcanic eruptions which were of unusual 

 severity that year. 



A somewhat similar fog appeared in the United States, 

 a portion of Europe, and Africa in August, 1831. The day- 

 light was perceptibly diminished, while at night a con- 

 spicuous phosphorescent light was emitted. A remarkable 

 luminous fog occurred in Switzerland in 1859. M. L. F. 

 Wartmann of Geneva states that the strange light was 

 observed on five successive nights, and apparently proceeded 

 from a heavy dry fog that hung over Geneva during the 

 time. The light was so brilliant that this gentleman dis- 

 tinguished the smallest objects upon his table with perfect 

 ease, no other light being in the apartment. The light 

 caused general comment in the places in which it appeared, 

 and a traveller between Geneva and Annemassi stated that 

 he readily found the road by its means. Dr. Verdeil of 

 Lausanne describes a fog which diffused so much light 

 that distant objects were perfectly visible at night. 



Among the phenomena which attended the eruption of 

 Vesuvius in 1794 was one which did not tend to allay the 

 fears of the people. During the day a fine dust filled the 



