world's age is the
outgrowth and offspring of all preceding years. Science proves itself
to be a genuine product of Nature by growing according to this law. We
have no solution of continuity here. All great discoveries are duly
prepared for in two ways; first, by other discoveries which form their
prelude; and, secondly, by the sharpening of the inquiring intellect.
Thus Ptolemy grew out of Hipparchus, Copernicus out of both, Kepler
out of all three, and Newton out of all the four. Newton did not rise
suddenly from the sea-level of the intellect to his amazing elevation.
At the time that he appeared, the table-land of knowledge was already
high. He juts, it is true, above the table-land, as a massive peak;
still he is supported by the plateau, and a great part of his absolute
height is the height of humanity in his time. It is thus with the
discoveries of Kirchhoff. Much had been previously accomplished; this
he mastered, and then by the force of individual genius went beyond
it. He replaced uncertainty by certainty, vagueness by definiteness,
confusion by order; and I do not think that Newton has a surer claim
to the discoveries that have made his name immortal, than Kirchhoff
has to the credit of gathering up the fragmentary knowledge of his
time, of vastly extending it, and of infusing into it the life of
great principles.

With one additional point we will wind up our illustrations of the
principles of solar chemistry. Owing to the scattering of light by
matter floating mechanically in the earth's atmosphere, the sun is
seen not sharply defined, but surrounded by a luminous glare. Now, a
loud noise will drown a whisper, an intense light will overpower a
feeble one, and so this circumsolar glare prevents us from seeing many
striking appearances round the border of the sun. The glare is
abolished in total eclipses, when the moon comes between the earth and
the sun, and there are then seen a series of rose-coloured
protuberances, stretching sometimes tens of thousands of miles beyond
the dark edge of the moon. They are described by Vassenius in the
'Philosophical Transactions' for 1733; and were probably observed even
earlier than this. In 1842 they attracted great attention, and were
then compared to Alpine snow-peaks reddened by the evening sun. That
these prominences are flaming gas, and principally hydrogen gas, was
first proved by M. Janssen during an eclipse observed in India, on the
18th of August, 1868.

But