THE VOLCANIC ERUPTION OF KRAKATAU. 375 



amined a large number of barographs, from which he has been able 

 to fix the dates at which the atmospheric undulations passed various 

 places on the earth's surface. As in the sea, so in the air, two waves, 

 one to the east and one to the west, started from Krakatau, whose rate 

 of progress has been found to be that of sound. One surprising circum- 

 stance, of which we have as yet observed no explanation, is how those 

 ships which were near the volcano at the moment of the supreme ex- 

 plosions, of the enormity of which they seem not to have been cogni- 

 zant, notwithstanding that they were heard at such immense distances, 

 did not only not suffer from the concussion, but were not blown off 

 the face of the water altogether. Almost coincident with the record 

 of the abnormal atmospheric fluctuations, magnificent sunlight effects, 

 unusually lurid skies, prolonged dawns, lengthened twilights, and 

 green or blue or moon-like suns, began to be observed. From the 

 dates at which these phenomena first appeared in different parts of 

 the world — on the east coast of Africa on the second day, the Gold 

 Coast on the third, Trinidad on the sixth day, at four thousand miles 

 in the Pacific west of Panama on the seventh, and at Honolulu on 

 the ninth day — it can be seen that the volcanic cloud followed a 

 straight path. 



To what height the supreme outburst propelled the smoke, dust, 

 and the lighter portion of matter, it is impossible at present to esti- 

 mate. Mr. Whymper saw Cotopaxi, in by no means one of its extraor- 

 dinary expirations, eject a column over 20,000 feet in height ; but 

 many multiples of this distance will doubtless be required to measure 

 the spire that was shot sky-ward on the forenoon of the 27th of August 

 last. At all events it rose so high that months have been required for 

 it to descend. Those places situated below the direct westward path 

 of the cloud, which would be elevated at first as a narrow column, as 

 they were carried under it by the eastward rotation of the earth, were 

 the first to have the usual light of the sun changed into ominous dis- 

 plays or delightful after-glows, varying in intensity according to their 

 time-distance away, and therefore to the amount of the obstructing 

 dust, which would also condense moisture in the upper part of the air, 

 and give special absorption effects,* that had by the hour they were 

 reached subsided from the atmosphere. This narrow band, gradually 

 spreading out north and south, enabled the inhabitants of all lands to 

 obtain a view of the gorgeous effects of broken and absorbed sun- 

 beams, and a demonstration of the vastness of the power of impris- 

 oned steam. 



Many questions connected with the subject remain at present un- 

 explained ; but the difficulties will in great part doubtless disappear 

 before our fuller information. A committee of the Royal Society, 

 consisting of our highest authorities in meteorological, volcanic, and 

 light phenomena, has, as we have said, been appointed to fully investi- 

 * Cf. " Nature," February 21, 1884, pp. 381, 882. 



