VULCANOI.' GY AND SKISMOLOGY. 217 



its influence to tlio coasts of America, where it was plainly marked on 

 the tide-gauges in California and Alaska. On Java the whole west 

 coast was swept by the wave, and the town and light-house of Anjer 

 were completely destroyed, the wave there reaching a height of over 30 

 meters. In Lampong liay, Sumatra, a Government vessel was carried 

 three miles inland, and the hay was so filled with floating pumice that 

 for weeks afterward vessels were unable to aproach the site of the 

 ruined town of Telok Betong, at its head. Up to November 1, 32,635 

 victims of the catastiophe were counted. 



The velocity of this ocean wave in its progress to distant stations 

 was investigated by several persons. It was propagated most forcibly 

 toward the Indian Ocean, and was distinctly marked at twelve of the 

 seventeen Indian tidal stations, as well as at Port Louis, in Mauritius, 

 and Port Elizabeth, in South Africa. For the two latter places Maj. A. 

 W. Baird deduces the velocity of 467 statute miles per hour {Nature, 

 XXIX, 358), both giving the same result, although the distances are 3,400 

 and 5,450 miles, respectively. This agrees with Airy's tabulated value 

 for an ocean depth of 15,000 feet, which is supposed to be the average 

 depth in this direction. The velocities in other directions were less, 

 viz, to Galle, 397 miles; toNegapatam, 355 miles; and to Aden, 371 miles. 

 Verbeelv deduced a velocity of only 306 miles per hour to Port Eliza- 

 beth and 109 miles to Padang. {Nature, xxx, 10.) 



Another aud unexpected result of the Krakatoa explosion was the 

 formation of an immense air wave, which was ])ropagated several times 

 about the earth in both directions, making its i)assage known by irregu- 

 larities in the traces of the recording barometers in numerous meteor- 

 ological observatories in all parts of the world. It was first recognized 

 by General Eichard Strachey {Nature, xxix, 181), in a i)aper presented 

 to the Boyal Society in December, 1883, and later investigations abun- 

 dantly confirmed his deductions. The wave made the circuit of the 

 earth in about thirty-six hours, having thus a velocity approximating 

 that of sound. The wave propagated from east to west had a mean pe- 

 riod of 36^ 57°", that from west to east 35^> 17'", the difference being at- 

 tributed to the motion of the atmosphere. The wave returned to the 

 same station three or four times, gradually becoming imperceptible. 



The far-reaching effects of the Krakatoa explosion have been traced 

 in still another direction in the peculiar ruddy appearance of the sky at 

 sunset and at sunrise. This first attracted general attention in America 

 and Europe in the latter part of November, 1883. Many causes were 

 suggested, and much discussion filled the scientific periodicals about 

 them, but it has been pretty generally accepted that the apjiearances 

 were due to the presence in the ui)per atmosphere of fine dust from 

 Krakatoa. In support of this view are the facts that distinct evidence 

 of volcanic dust, similar to that ejected from Krakatoa, has been found 

 in rain and anow, and that the successive ai)pearances of the red skies 

 could be traced around the globe as the dust cloud gradually extended 



