PHYSICS OF THE GLOBE. 185 



self and disappeared in the peat bank. Its total duration was 

 about 20 minutes. It appeared about 2 feet in diameter at 

 first, but gradually diminished to 3 inches. The sky was clear 

 at the time. Wherever it touched the ground in its course, 

 it ploughed up the earth to a depth of several feet. In the 

 discussion on this report, Mr. Symons stated that forked 

 lightning and globular lightning were, he thought, the same. 



The Scientific Gazette for Venezuela publishes a communi- 

 cation to the Physical Society of Caraccas, by J. M. Tebar, 

 on an Electric Phenomenon peculiar to Lake Zulia, called 

 the Farol cle Maracaibo. He explains this light as being an 

 electric phenomenon due to a quiet discharge of a large extent 

 of atmosphere of the negative electricity with which ascend- 

 ing currents of air are saturated, while the descending cur- 

 rents are charged with positive electricity. The same jour- 

 nal contains an original theory, accompanied by some math- 

 ematical demonstrations, relative to the Nebular Hypothesis, 

 by E. Ricard. 



Hildebrandsson has published an Investigation into the 

 Thunder-storms of Sweden, based on observations at about 

 250 stations, from 1871 to 1875. He distinguishes between 

 the thunder-storms that attend the advancing sides of ex- 

 tensive storms (the Wirbelgeicitter) and those that originate 

 in overheated districts (the Wcirmegewitter). Similar classi- 

 fications have been made by Mohn in Norway and Fron in 

 France, and are occasionally alluded to in the weather reviews 

 of the Army Signal-Office. Scarcely a single instance was 

 recorded in the five years in which it could not be shown 

 that the so-called "heat" or "sheet" lightning was simply 

 the reflection of lightning so far distant that the thunder 

 was inaudible, or possibly refracted above the observer's ear. 



Dr. Pissis publishes in his "Physical Geography of the Re- 

 public of Chili" some notes on thunder-storms in that state. 

 Destructive thunder-storms are unknown in the inhabited 

 portions of the state, but are of daily occurrence among the 

 mountains. In the morning a small cloud forms around eacli 

 summit, which soon increases to a large cumulus, and event- 

 ually extends over the whole range of peaks. In the after- 

 noon fearful thunder and lightning occur; and, high np the 

 mountain-sides, snow and hail. The hail and snow are phos- 

 phorescent, as it were, with electricity. The storms on the 



