The Eruption of Krakatoa 



203 



part of our atmosphere had been set 

 into a tingle by the great eruption. In 

 Great Britain the waves passed over our 

 heads, the air in our streets, the air in 

 our houses, trembled from the volcanic 

 impulse. The very oxygen supplying 

 our lungs was responding also to the 

 supreme convulsion which took place 

 10,000 miles away. It is needless to 

 object that this could not have taken 

 place because we did not feel it. Self- 

 registering barometers have enabled 

 these waves to be followed unmistak- 

 ably all over the globe. 



Such was the energy with which these 

 vibrations were initiated at Krakatoa, 

 that even when the waves thus arising 

 had converged to the point diametrically 

 opposite in South America their vigor 

 was not yet exhausted. The waves 

 were then, strange to say, reflected back 

 from their point of convergence to re- 

 trace their steps to Krakatoa. Starting 

 from Central- America, they again de- 

 scribed a series of enlarging circles, 

 until they embraced the whole earth. 

 Then, advancing into the opposite hem- 

 isphere, they gradually contracted until 

 they had regained the Straits of Sunda, 

 from which they had set forth about 

 thirty-six hours previously. Here was, 

 indeed, a unique experience. The air 

 waves had twice gone from end to end 

 of this globe of ours. Even then the 

 atmosphere did not subside until, after 

 some more oscillations of gradually 

 fading intensity, at last the}' became 

 evanescent. 



But, besides these phenomenal undu- 

 lations, this mighty incident at Kra- 

 katoa has taught us other lessons on the 

 constitution of our atmosphere. We 

 previously knew little, or I might almost 

 say nothing, as to the conditions pre- 

 vailing above the height of ten miles 

 overhead. We were almost altogether 

 ignorant of what the wind might be at 

 an altitude of, let us say, twenty miles. 

 It was Krakatoa which first gave us a 

 little information which was greatly 



wanted. How could we learn what 

 winds were blowing at a height four 

 times as great as the loftiest mountain 

 on the earth and twice as great as the 

 loftiest altitude to which a balloon has 

 ever soared. We could neither see 

 these winds nor feel them. How, then, 

 r could we learn whether they really ex- 

 isted ? No doubt, a straw will show 

 the way the wind blows; but there are 

 no straws up there. There was nothing 

 to render the winds perceptible until 

 Krakatoa came to our aid. Krakatoa 

 drove into those winds prodigious quan- 

 tities of dust. Hundreds of cubic miles 

 of air were thus deprived of that invis- 

 ibility which they had hitherto main- 

 tained. They were thus compelled to 

 disclose those movements about which, 

 neither before nor since, have we had 

 any opportunity of learning. 



With eyes full of astonishment, men 

 watched those vast volumes of Krakatoa 

 dust start on a tremendous journey. 

 Westward the dust of Krakatoa took 

 its way. Of course, every one knows 

 the so-called trade-winds on our earth's 

 surface, which blow steadily in fixed 

 directions and which are of such service 

 to the mariner ; but there is yet another 

 constant wind. We cannot call it a 

 trade-wind, for it never has rendered 

 and never will render any sendee to 

 navigation. It was first disclosed by 

 Krakatoa. Before the occurrence of 

 that eruption no one had the slightest 

 suspicion that far up aloft, twenty miles 

 over our heads, a mighty tempest is in- 

 cessantly hurrying with a speed much 

 greater than that of the awful hurricane 

 which once laid so large a part of Cal- 

 cutta on the ground and slew so many 

 of its inhabitants. Fortunately for hu- 

 manity, this new trade-wind does not 

 come within less than twenty miles of 

 the earth's surface. We are thus pre- 

 served from the fearful destruction that 

 its unintermittent blasts would pro- 

 duce — blasts against which no tree could 

 stand and which would, in ten minutes, 



