which reflects most of the blue rays away from us, leaving the
complementary yellow light to pass on. Then, the somewhat coarser dust
reflects the green rays, leaving a more orange coloured light to pass
on; and finally some of the yellow is reflected, leaving almost pure
red. But owing to the constant presence of air currents, arranging both
the dust and vapour in strata of varying extent and density, and of high
or low clouds, which both absorb and reflect the light in varying
degrees, we see produced all those wondrous combinations of tints and
those gorgeous ever-changing colours, which are a constant source of
admiration and delight to all who have the advantage of an uninterrupted
view to the west, and who are accustomed to watch for these not
unfrequent exhibitions of nature's kaleidoscopic colour-painting. With
every change in the altitude of the sun the display changes its
character; and most of all when it has sunk below the horizon, and,
owing to the more favourable angles, a larger quantity of the coloured
light is reflected toward us. Especially is this the case when there is
a certain amount of cloud. The clouds, so long as the sun is above the
horizon, intercept much of the light and colour; but, when the great
luminary has passed away from our direct vision, his light shines more
directly on the under sides of all the clouds and air strata of
different densities; a new and more brilliant light flushes the western
sky, and a display of gorgeous ever-changing tints occurs which are at
once the delight of the beholder and the despair of the artist. And all
this unsurpassable glory we owe to--dust!

A remarkable confirmation of this theory was given during the two or
three years after the great eruption of Krakatoa, near Java. The
volcanic débris was shot up from the crater many miles high, and the
heavier portion of it fell upon the sea for several hundred miles
around, and was found to be mainly composed of very thin flakes of