374 THE POPULAR SCIENCE MONTHLY. 



Island, and plunged it into the sea some seven miles to the northeast, 

 where Calmeyer Island now blocks the channel which mariners have 

 known so long as the East Passage. 



The reports we have as to the tidal phenomena differ from differ- 

 ent places. At many points it was observed that a distinct with- 

 drawal of the water preceded the rise or great tide ; while from others, 

 as in the canal at Batavia, the opposite is given as the order of 

 occurrence. Everything, however, depends on the moment of the 

 observation. It will be apparent that these waves were the most nat- 

 ural consequents of the events, and were due certainly not to any 

 seismic movement of the sea-bed, but, on the one hand, to the in -rush 

 of water to,fill the deep chasms out of which the ejected portions of 

 the island came, which was naturally followed first by a withdrawal 

 of the water, and then by a disastrous recoil over the low fore-shores 

 of Java and Sumatra ; and on the other hand to the tremendous stroke 

 — the splash, in fact — imparted to the sea by such a gigantic block of 

 matter, square miles in size, which must have resulted first in a great 

 rise of water, followed by a withdrawal. 



It is a remarkable circumstance that in the logs of several ships 

 which were in the close vicinity of the volcano in the forenoon of the 

 2Tth, no mention is made of the great wave which proved so destruc- 

 tive, and which could scarcely, one conceives, have failed to attract 

 attention. May the explanation not lie in the supposition that these 

 two great waves — the in-rush and the splash waves — which would 

 follow each other after a short interval, had neutralized each other 

 at the spots where these vessels chanced to be at the moment ? 

 Issuing from the narrow straits into the oceans east and west, 

 these waves started off on their journey round the globe, and, from 

 the records of the tide-gauges which are now coming in, we have a 

 most remarkable tale unfolded. On the afternoon of the same day 

 that the greater of them swept away the Javan villages, the undu- 

 lations were registered unmistakably in Mauritius, the Seychelles, 

 in South Africa, and on the shores of the Pacific islands ; but, as Mr. 

 Lockyer informs us, they did not vanish there, but proceeded on- 

 ward, and, crossing each other on the antipodes of Krakatau, jour- 

 neyed back to the spot whence they had emanated, and this they did 

 no fewer than four times before the equilibrium of the sea was re- 

 stored so far as to be insensible to our instruments. While the tide- 

 gauges have recorded their story, the delicate fingers of the baromet- 

 rical registers of the world have also borne uninfluenced testimony of 

 a similar kind. The blow which hurled such a mass of matter into 

 the air, which originated a hurricane there and caused the barometers 

 in the neighborhood of the volcano to rise and fall with unparalleled 

 rapidity and a vessel distant three hundred miles to tremble, started 

 an atmospheric wave also round the globe. It was first detected in 

 the Kew registers, we believe, by General Strachey, who has now ex- 



