THOUGHTS ABOUT KRAKATOA. 325 



sounds are carried. Other more subtle, but not less 

 interesting, phenomena are the waves in the atmospheric 

 ocean, which are neither seen nor heard, but of which the 

 barometer gives no uncertain indications. Among the 

 remaining effects of a volcanic explosion are the curious 

 sunset glows and the strange optical phenomena which are 

 sometimes witnessed. We have thus a number of distinct 

 points of view from which the significance of a volcano 

 can be estimated. 



We had all heard so much about Krakatoa that at 

 first it is a little disappointing to read the assurances 

 of Professor Judd that, so far as the first two of these 

 standards are concerned, Krakatoa has been surpassed 

 by other volcanoes. He enumerates three distinct out- 

 breaksviz., that of Papandayang, in Java, in 1772; 

 of Skaptar Jokull (Yarmardalr), in Iceland, in 1783 ; 

 and of Tomboro, in Sumbawa, in 1815 in all of which 

 the quantity of matter poured forth was considerably 

 greater than that from Krakatoa. However, even in this 

 respect the achievements of Krakatoa if second-rate are at 

 least respectable. The estimates made are necessarily 

 founded on precarious data, but it seems to be certain that 

 if all the materials poured forth from Krakatoa during the 

 critical period could be collected together, the mass they 

 would form would be considerably over a cubic mile in 

 volume. It is in the other standards of comparison that 

 the importance of the explosion at Krakatoa is to be 

 sought. The intensity of this outbreak in its last throes 

 was such that mighty sounds were heard and mighty 

 waves arose in the sea for which we can find no parallel. 

 Every part of our globe's surface felt the pulse of the air- 



