Everywhere those great waves produced phenomena which were so striking as to attract the attention of all classes of people, to ensure record in most parts of the world, and to call for the earnest investigation of the scientific men of many lands—­and the conclusion to which such men have almost universally come is, that the strange vagaries of the sea all over the earth, the mysterious sounds heard in so many widely distant places, and the wonderful effects in the skies of every quarter of the globe, were all due to the eruption of the Krakatoa volcano in 1883.

With reference to these last—­the sky-effects-a few words may not be out of place here.

The superfine “ultra-microscopic” dust, which was blown by the volcano in quantities so enormous to such unusual heights, was, after dropping its heavier particles back to earth, caught by the breezes which always blow in the higher regions from east to west, and carried by them for many months round and round the world.  The dust was thickly and not widely spread at first, but as time went on it gradually extended itself on either side, becoming visible to more and more of earth’s inhabitants, and at the same time becoming necessarily less dense.

Through this medium the sun’s rays had to penetrate.  In so far as the dust-particles were opaque they would obscure these rays; where they were transparent or polished they would refract and reflect them.  That the material of which those dust-particles was composed was very various has been ascertained, proved, and recorded by the Krakatoa Committee.  The attempt to expound this matter would probably overtax the endurance of the average reader, yet it may interest all to know that this dust-cloud travelled westward within the tropics at the rate of about double the speed of an express train—­say 120 miles an hour; crossed the Indian Ocean and Africa in three days, the Atlantic in two, America in two, and, in short, put a girdle round the world in thirteen days.  Moreover, the cloud of dust was so big that it took two or three days to pass any given point.  During its second circumnavigation it was considerably spread and thinned, and the third time still more so, having expanded enough to include Europe and the greater part of North America.  It had thinned away altogether and disappeared in the spring of 1884.

Who has not seen—­at least read or heard of—­the gorgeous skies of the autumn of 1883?  Not only in Britain, but in all parts of the world, these same skies were seen, admired, and commented on as marvellous.  And so they were.  One of the chief peculiarities about them, besides their splendour, was the fact that they consisted chiefly of “afterglows”—­that is, an increase of light and splendour after the setting of the sun, when, in an ordinary state of things, the grey shadows of evening would have descended on the world.  Greenish-blue suns; pink clouds; bright yellow, orange, and crimson afterglows; gorgeous, magnificent, blood-red skies—­the commentators seemed unable to find language adequately to describe them.  Listen to a German observer’s remarks on the subject:—­