VULCANOLOGY AND SEISMOLOGY. 



By Charles G. Eockwood, Jr., Ph. D., 



Professor of Mathemalks in the College of N^ew Jersey, Privceton, N, J. 



The following snmniary for the years 1883 and 1884 cannot pretend 

 to be complete. Neitlier the i^pace nor the time at command would al- 

 low of even the mention of all that ha-s happened or all that has been 

 done and written in these departments in the two years. The writer has 

 therefore preferred to make somewhat more full the account of those 

 things which seemed most deserving of such record, even at the expense 

 of passing unnoticed many things of interest and much good work that 

 has been done, especially in foreign countries, where it is less accessi- 

 ble to an American writer. For all else the reader must refer to the 

 authorities mentioned in the bibliograi)hy. The subjects will be treated 

 in the following onler : 



Vulcanolngy : 



Volcanic eruptions of 1883 and 1884. 



Investigations of former volcanic activity. 

 Seismology : 



Earthquake lists of 1882 and 1S83. 



Special earthquakes of 1883 and 1884. 



Lists of former earthquakes. 



Theories of earthquakes. 

 Seismometry : 



Instruments and their records. 



VULCANOLOGY. 



In the last days of August, 1883, the Straits of Sunda were the scene 

 of a catastrophe exceeding in magnitude and destructiveness anything 

 that has heretofore come within the observation of civilized men. It has 

 been the subject of numerous publicacions in the various languages (see 

 bibliography,) from which tlie following condeused account is drawn: 



The island of Krakatoa lies midway between Java and Sunuitra, in 

 the Strait of Sunda. It was about five miles long by three miles wide, 

 rising into a triple mountain i)eak 2,700 feet higli, and clothed with veg- 

 etation from l)ase to summit. Near it are two small islands, Verlaten 



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