he luminous substance is
made visible to us is gaseous. If it were liquid, the light would be
coloured; and as regards solidity, that is out of the question--the
rapid change of spots proves that the outer envelope of the sun is not
solid. On whatever day of the year we examine, the light is always
white. Thus, these experiments remove the theory out of the region of
simple hypothesis, and give certainty to our conclusions respecting
the photosphere.

Here an example occurs of the aids and confirmations which science may
derive from apparently trivial circumstances. Complaint was made at a
large warehouse in Paris, that the gas-fitters had thrown the light on
the goods from the narrow, and not from the broad side of the flame.
Experiments were instituted, which proved that the amount of light was
the same whether emitted from the broad or narrow surface. It was
shewn also, that a gaseous substance in flame appears more luminous
when seen obliquely than perpendicular, which explains what are known
as _faculae_ and _lucules_, being those parts of the solar disk that
shew themselves brighter than other portions of the surface. These are
due to the presence of clouds in the solar atmosphere; the inclined
portions of the clouds appearing brightest to the spectator. The
notion, that there were thousands on thousands of points
distinguishing themselves from the rest by a greater accumulation of
luminous matter, is thus disposed of.

Still, there remained something more to be determined. The existence
of the photosphere being proved, the question arose--was there nothing
beyond? or did it end abruptly? and this could only be determined at
the period of a total eclipse, at the very moment when the obscuration
of the sun being greatest, our atmosphere ceases to be illuminated.
Hence the interest felt in an eclipse of the sun of late years.

In July 1842, at a total eclipse of the sun visible in several parts
of the continent, the astronomers noticed, just as the sun was hidden
by the moon, certain objects, in the form of rose-coloured
protuberances, about two or three minutes high, astronomically
speaking, projected from the surface of the moon. These appearances
were variously explained: some supposed them to be lunar mountains;
others saw in them effects of refraction or diffraction; but no
precise explanation could be given; and mere guesses cannot be
accepted as science. Others, again, thought them to be mountains in
the