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The National Geographic Magazine 



carpments remaining, were composed 

 of unconsolidated debris, deposited for 

 the most part directlj' by streams as 

 deltas. This loose material, resting on 

 the steeply inclined rocks beneath, was 

 in a position to be easily dislodged by 

 earthquake shocks, by the rush of mud 

 avalanches down the valley, at the 

 mouths of which the deposits had been 

 made, and by the return waves when 

 the sea was disturbed by the volcanic 

 blasts or by mud avalanches. The 

 changes made by subsidence of the 

 land are not great, and, as several ob- 

 servers have stated, may reasonably 

 be accounted for in the manner just 

 referred to. 



Electrical Displays. — The graphic ac- 

 counts that have been published of the 

 recent eruption give a better idea of 

 the magnificence of the electrical phe- 

 nomena accompanying volcanic explo- 

 sions than was previous^ attainable. 

 These observations show that an in- 

 teresting and difficult problem here 

 awaits solution. The most striking 

 phase of what is assumed to have been 

 an electrical display during a primary 

 eruption of Mont Pelee on the evening 

 of May 26 is thus described by George 

 Kennan : 



"The feature of the eruption that 

 made the deepest impression upon me 

 was the stellar lightning. The uprush 

 of black smoke, the glow over the 

 crater, and the shower of incandescent 

 stones and cinders were all phenomena 

 that had been observed and described 

 before; but the short, thin streaks of 

 lightning, followed by star-like explo- 

 sions in the volcanic mantle — not only 

 above the crater, but miles away from 

 it — were entirely new. The distinctive 

 characteristics of this lightning were 

 the shortness of the streak, the com- 

 paratively great size and brilliancy of 

 the spark, or light-burst, at the end of 

 the streak, and the single booming re- 

 port that followed. Sometimes three 

 or four great sparks, connected by fiery 



streaks, would flash together in this 

 way; and at other times the stars would 

 burst so far back in the cloud that the 

 streaks were invisible and there was 

 onby a circular irradiation of the vapor. 

 If there was any storm lightning, of 

 the ordinary kind, in the earlier stages 

 of the eruption, it was so much less 

 noticeable than the stellar lightning 

 that it escaped my observation; and I 

 am quite sure that there was no rolling, 

 reverberating thunder at all until near 

 the close of the displa3 - , when reddish 

 lightning-bolts began to dart down on 

 the volcano from the developing storm- 

 cloud over the crater. Before that time 

 all, or nearly all, of the electric dis- 

 charges had ended in stellar light-bursts, 

 and all of the thunder had been made 

 up of separate and distinct reports, like 

 the thunder of a heavy and rapid can- 

 nonade." 



In reading this account one can 

 scarcely avoid making the tentative 

 suggestion that the streaks of light and 

 brilliant explosions, apparently resem- 

 bling the trails and occasional bursting 

 caused by meteoric bodies entering the 

 earth's atmosphere, may have been due 

 to intensely heated solid particles on 

 entering the oxygen-charged air. 



Other Phenomena . — A final report on 

 the recent and still continuing eruptions 

 of Mont Pelee and I^a Soufriere must 

 include the evidence in reference to; the 

 sounds generated, the earthquake 

 shocks, the areas on which dust fell 

 and its relation to the direction and 

 force of air currents, gravity waves in 

 the air, influence of dust in the air on 

 sunlight, and, most interesting of all as 

 well as the most novel, the magnetic 

 waves generated, some of which were 

 recorded almost instantaneously at sev- 

 eral magnetic stations in the United 

 States and Canada. 



The Studv of the Earth ' s Interior. — 

 Perhaps the chief lesson taught by the 

 recent volcanic eruptions in the Antilles 

 is the meagerness of our knowledge 



