xxxii GENERAL SUMMARY OF SCIENTIFIC AND 



surfaces of the earth, the atmosphere being electrified by in- 

 duction ; the consequence deduced by him that no electrical 

 development should be perceptible in the polar regions is a 

 fact attested by all arctic explorers. 



Among the more noteworthy auroras of America we re- 

 cord those of February 4th, April 7th, and October 3d and 

 4th; and Mr. Abbe calls attention to the fact that in a vast 

 majority of cases the region over which an aurora is visible 

 is bounded on the east, south, and west by a region within 

 which lightning is simultaneously occurring. 



To the general catalogues of auroras another has been add- 

 ed by Fritz, who has also contributed a remarkably accurate 

 chart of auroral frequency, with which he has coupled some 

 suggestions; while Groneman has developed very fully his 

 own theory as to the cosmical origin of the aurora. 



Seismology. The year has been signalized by the occur- 

 rence of several important earthquakes, of which we may 

 mention the folio win o- ; 



In North Carolina, sixty slight shocks from February to 

 April. 



Violent shocks at Antigua on September 3d ; and in Sicily, 

 September 27. 



Strong shocks in Constantinople, June 26 ; Utah, June 18 ; 

 Malta, October 18; Ceylon, September 19; Vera Cruz, Nov. 13. 



Notable volcanic eruptions occurred August 10-20 in Ja- 

 pan; September 1, etc., Mount Etna; April 30, Society Islands. 



Mallet has published a continuation of his seismic investi- 

 gations, and deduces an approximate determination of the 

 rate of contraction of the earth's radius, namely, 3.5 inches in 

 5000 years; and has, in an interesting note on the volcano of 

 Stromboli, "given a detailed explanation of its mechanism, and 

 a refutation of the idea that its eruptions depend upon at- 

 mospheric changes. 



La Faulx and Kortum have given a somewhat minute ex- 

 amination of the phenomena of the German earthquake of 

 October 22, 1873. 



Schmick has investigated the changes in the level of the Cas- 

 pian and Aral basin in the light of the theory of the secular 

 variations in the sea-level and the tropic zones; a more general 

 note on this subject is published by Mr. Hind, of Nova Scotia. 



Mr. Clingman has given, in the New York 7 7 hnes, July 



