would become encrusted with a solid shell
whose Ætnas and Vesuviuses, whose German
and Pyreneean thermal waters betray the fires
still smouldering within. We are, fortunately
for us, behindhand with regard to the moon,
but considerably in advance of the sun. Every
heavenly body must undergo the same successive
transformations in the eternal harmony of
the universe.

Another mode of investigating the sun's
constitution is the observation of total eclipses.
At such times, the moon, by screening almost
the whole of the solar disc, prevents the
observer from being blinded by excess of light.
The outline and profile of the sun, which could
not be examined under ordinary circumstances,
are then distinguished with perfect clearness.
During the eclipse of 1860 the French
astronomers who went to Spain distinctly saw the
different peculiarities presented by the brilliant
crown which surrounds the moon's black disc.
In the middle of the luminous ring they
perceived what looked like pink or red clouds.

These "protuberances," to retain the name
first given to them, appeared under very varied
guise. Before the eclipse of 1860, some
observers were inclined to take them for the
summits of exceedingly lofty mountains rising
above the solar atmosphere. But after it,
doubt was no longer possible. The semblances
of mountain peaks, it is true, were seen; but
pointed were less frequent than rounded and
lengthy forms. Many protuberances, moreover,
were absolutely detached from the sun, like the
cumulus clouds which float in our atmosphere.
Others were bent in a sidewise direction,
recalling flames under the influence of a current
of air. A few French savans considered the
protuberances as optical illusions produced by
the moon's interposition; but the majority
regarded them as appendages composed of fiery
vapours streaming into the upper regions of the
solar atmosphere. Spectral analysis, still in its
infancy, had not yet said its say.

The eclipse of 1868 was therefore impatiently
awaited. M. Janssen, well known by his
spectroscopic researches, directed his course to
Masulipatam. Afterwards, advised by persons
who knew the country, he determined to
proceed to Guntoor. Scarcely a week after the
event, he sent by telegraph the agreeable news,
"Eclipse well observed; protuberances
gaseous." M. Stéphan, who directed the Malacca
expedition, announced, a month afterwards,
that four protuberances had been seen on the
corona, and their gaseous nature determined
by their spectrum. Moreover, from the undue
prolongation of brilliant lines in the spectrum,
M. Rayet deduced the conclusion that a certain
portion of the incandescent gaseous matter of
which the protuberances consist, extends to a
height in the solar atmosphere beyond the
limits assigned to it by human eyes.

In a letter to the Minister of Public
Instruction, dated 19th September, M. Janssen
wrote: " Not having the time to send a
detailed account to-day, I will have the honour
of doing so by next post. Guntoor has
doubtless been the most favoured station.

The sky was clear, especially during the
totality, and my powerful nine-feet-focus
telescopes allowed me to pursue the analytical
study of all the phenomena of the eclipse.
Immediately after the totality, two magnificent
protuberances appeared: one of them, more
than three minutes in height, shone with a
splendour difficult to conceive. The analysis
of its light immediately informed me that it
consisted of an immense incandescent gaseous
column, principally composed of hydrogen.

"But the most important result of these
observations is the discovery of a method
which suggested itself during the actual
occurrence of the eclipse, and which permits the
study of the protuberances and the circumsolar
regions at all times, without having to wait for
the passage of an opaque body in front of the
sun's disc.

"The very day after the eclipse, the new
method was successfully put in practice, and I
was able to witness the phenomena presented
by a fresh eclipse, which lasted the whole day
long. Yesterday's protuberances were
profoundly modified. Of the grand protuberance
there scarcely remained a trace, and the
distribution of the gaseous matter was quite different
to what it had been. From that day up to the
4th of September I have constantly studied the
sun with this object in view. I have drawn up
maps of the protuberances, which show with
what rapidity (often in a few minutes) these
immense masses of gas change their form and
place. Lastly, during this period, which has
been, as it were, an eclipse lasting seventeen
days, I have collected a great number of facts,
which presented themselves spontaneously,
respecting the physical constitution of the
sun."

M. Janssen's method, like Columbus's finding
America, will appear very simple now it is
known. On looking at the sun near its outer
edge, but a little outside it, where the
protuberances show themselves, it is clear that not
only the radiations from the great luminary
itself will meet the eye, but also, mingled with
them, the light of the protuberances. Consequently,
the spectrum of the mixed radiations
ought to contain both the black stripes of the
solar rays and the bright stripes of the
protuberances. And, in fact, when M. Janssen had
recognised the bright lines of the protuberances,
he found them again below the black lines of
the solar spectrum and in their prolongations.
Consequently, there are two systems of lines:
one lying above the other. By reading the
lower scale, you have before you the characteristic
features of the protuberances. But we do
not yet know our spectral alphabet; we are
only beginning to learn to read.

M. Janssen expressses his high appreciation
of the reception given him by the English
authorities in India. A steamer was placed at
his disposal to take him from Madras to
Masulipatam; another for the Godavery; and a young sub-collector was attached to his mission, to
smooth any difficulties that might arise. He
ought now to have reached Calcutta, and
proposes to carry out in the Himalayas certain