SUMATEA 169 



it, but to the south-east the tide gauges of West Australia 

 showed marked evidences of its having reached those 

 shores. 



Still more extraordinary were the air waves produced 

 by the violent explosions. Here, again, we find, as in the 

 case of the sea waves, that there was one pre-eminent in 

 strength and volume. It appears very nearly to have 

 coincided with the gigantic seismic wave just discussed, 

 and the character of the disturbance would seem almost 

 incredible, were it not for the fact that it is attested by 

 the barograms of every great meteorological station on the 

 world's surface. Shortly, it was this : that the circular 

 wave or oscillation having Krakatau as its centre pro- 

 pagated itself over the entire surface of the globe until it 

 reached the antipodes of the volcano ; that it was thence 

 reflected back or reproduced, travelling backwards to its 

 point of origin, from which it again returned ; and that 

 in this manner the occurrence of the wave was observed 

 no fewer than seven times — four passages having been 

 those of the wave travelling from Krakatau, and three 

 those of the wave travelling from its antipodes. From 

 this the time of its genesis could easily be calculated with 

 tolerable exactitude. It is given by Lieutenant-General 

 Strachey as 2 hours 56 minutes Greenwich mean time, 

 which in local time would correspond with 9.58 o'clock 

 on the morning of the 27th August. 



The distance at which the sounds of the eruption were 

 audible is much in excess of anything previously recorded ; 

 indeed, one of the reports is of special interest, as being 

 the only instance known of sounds being heard at any- 

 thing like so great a distance from their place of origin. 

 The island of Eodriguez in the Indian Ocean is about 

 2968 miles from Krakatau in a direct line, yet the noise 

 of the explosions was heard during the night of the 26th- 



