oa 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 commen