THE GRAND ERUPTION OF VESUVIUS IN igo6 64- 



that the steam as it is condensed by expansion to water vapor becomes 

 positively electrified. Many samples of the Vesuvian sabbia from 

 different localities when washed and heated were found to become 

 negatively electrified. He thus found an experimental explanation 

 for the origin of the atmospheric electricity developed during eruptions. 



Disturbances of the sea. 

 —On the 5th of April, 

 when the violent stage of 

 the eruption may be said 

 to have commenced, the 

 Bay of Naples is said to 

 have been in unusual 

 agitation, without appar- 

 ent explanation of the 

 weather conditions of that 

 or earlier days. On the 

 6th a tidal wave struck 

 the "Barbarossa" one 

 day out from New York 

 en route to Naples. It 

 seems unlikely that 

 either of these phenomena 

 was directly the result of 

 disturbances within the 

 crater of Vesuvius, and 

 it is far more probable 

 that they were attribut- 

 able to a more or less 

 distant seaquake, which 

 we may be able to locate 

 when the next report of 

 the seismological stations 

 co-ordinated under the 

 British Association has been issued. The time of the Vesuvian erup- 

 tion falls so nearly in coincidence with the earthquakes of California, 

 Hawaii, and Formosa that relationships of tidal disturbances are 

 otherwise difficult to trace. 



Fig. 8. — View of the "Pine Cloud" over Vesuvius 

 on April 11. View taken from Ponte della Gatta 

 looking over the ancient bocca of Camaldali della 

 Torre. 



