“The display of November 29th was the grandest and most manifold.  I give a description as exactly; as possible, for its overwhelming magnificence still presents itself to me as if it had been yesterday.  When the sun had set about a quarter of an hour, there was not much afterglow, but I had observed a remarkably yellow bow in the south, about 10 deg. above the horizon.  In about ten minutes more this arc rose pretty quickly, extended itself all over the east and up to and beyond the zenith.  The sailors declared, ‘Sir, that is the Northern Lights.’  I thought I had never seen Northern Lights in greater splendour.  After five minutes more the-light had faded, though not vanished, in the east and south, and the finest purple-red rose up in the south-west; one could imagine one’s-self in Fairyland.”

All this, and a great deal more, was caused by the dust of Krakatoa!

“But how—­how—­why?” exclaims an impatient and puzzled reader.

“Ay—­there’s the rub.”  Rubbing, by the way, may have had something to do with it.  At all events we are safe to say that whatever there was of electricity in the matter resulted from friction.

Here is what the men of science say—­as far as we can gather and condense.

The fine dust blown out of Krakatoa was found, under the microscope, to consist of excessively thin, transparent plates or irregular specks of pumice—­which inconceivably minute fragments were caused by enormous steam pressure in the interior and the sudden expansion of the masses blown out into the atmosphere.  Of this glassy dust, that which was blown into the regions beyond the clouds must have been much finer even than that which was examined.  These glass fragments were said by Dr. Fluegel to contain either innumerable air-bubbles or minute needle-like crystals, or both.  Small though these vesicles were when ejected from the volcano, they would become still smaller by bursting when they suddenly reached a much lower pressure of atmosphere at a great height.  Some of them, however, owing to tenacity of material and other causes, might have failed to burst and would remain floating in the upper air as perfect microscopic glass balloons.  Thus the dust was a mass of particles of every conceivable shape, and so fine that no watches, boxes, or instruments were tight enough to exclude from their interior even that portion of the dust which was heavy enough to remain on earth!

Now, to the unscientific reader it is useless to say more than that the innumerable and varied positions of these glassy particles, some transparent, others semi-transparent or opaque, reflecting the sun’s rays in different directions, with a complex modification of colour and effect resulting from the blueness of the sky, the condition of the atmosphere, and many other causes—­all combined to produce the remarkable appearances of light and colour which aroused the admiration and wonder of the world in 1883.