The Sun.
London, England, 1860-07-19 00:00:00

FROM A CORRESPONDENT OF TIIE POST.

Whether the astronomers stationed in various
parts of Spain and Algeria haye attained the object
of their anxious and laborious mission must for a
few days at least remain a subject of uncertainty,
regarding which it would be well to avoid alike
sanguine and desponding presumptions. In London
and its neighbourhood the sky was most unpropi-
tious, and at no period of the eclipse was the con-
stellation of the two planets visible quite free from
clouds, although at times only so thin a stratum of
watery vapours intervened between the planets and
the eye as to admit of a fair inspection of the phe-
nomenon. Shortly before the period of the greatest
phase of the eclipse the temperature sank consider-
ably, and the air came into irregular comm•tion.
At that period all chance of observation with mag-
nifying instruments seemed lost, as dense masses of
clouds, probably produced by the fall of the tem-
perature, drove up from the west, and eclipsed both
sun and moon together. But shortly after the
greatest phase some intervals ensued, during which
a fair telescopic view of the rugged dark outline of
the moon, as projected upon the crescent of the sun,
could he obtained. As the moon receded, a solar
spot of considerable diameter was uncovered, and
diversified a trifle the monotony of the telescopic
view. But soon a general spreading of high white
clouds closed up the heavens, and prevented all fur-
• ther observation.

As we have promised our readers an account of
the observations which we hope our astronomers
have now enriched science with, it may not be amiss
to recapitulate some former observations of eclipses,
by which the red prominences on the margin of the
sun first became a question of science. During the
total eclipse of July 8, 1842, Arago and other
astronomers observed dark or feebly-illuminated
clouds, which he supposed to be situated upon the cir-
cumference of the sun, or at a trifling distance from
it. These clouds had a ruby or rose-red colour ac-
cording to some observers, and were assumed by
Arago to belong to a third outer sphere, or solar
envelope, consisting of gas, and having a somewhat
imperfect transparency, according to Sir John
Herschel. The total eclipse of the sun of July 28,
1831, contributed many facts confirming the
opinion of Arago. To the account of the observa-
tions of the Astronomer Royal and M. Otto Struve
we have to add a notice of those of Dr. Galle, who
on that occasion was stationed at Frauenburg. He
saw little detached clouds, which, by means of two
or three threads, were connected with the hook-
shaped gibbosity. This hook-shaped excrescence
corresponds to what in England has been termed
the boomerang. The marginal excresences could be
seen by means of the telescope, although slight
clouds of the terrestrial atmosphere intervened, and
could be identified within the corona with the
naked eye. During the totality of the eclipse they
quickly changed their shape. Dr. Lamont sup-
poses these red prominences to be produced by thin
clouds, or masses of vapour, floating in ohr atmo-
sphere, and condensed by the depression of tem-
perature in the shadow of the moon. He thinks
that all the phenomena which have been recorded
agree perfectly with this explanation, and he has
no doubt that in a hot climate, where the air con-
tains a large quantity of vapour, it will be possible,
by using a telescope of low magnifying power and
considerable aperture, to trace these clouds to a
much greater distance than has yet been done, and
to prove by their motion and changes that they do
not belong to the sun.
The prominences were last observed by Lieu-
tenant J. M. Gilliss, U.S.. during the total eclipse
of the sun on September 7, 1858, observed by him
from a station near Olmos, Peru. He states that
the night of the 6th, and until daylight of the
morning of the 7th of September was bright and
faultless; but just before sunrise a few banks of
heavy cumuli formed over and near the distant
mountains to the eastward, the part of the sky least
obscured being in the (Frection of the sun. Some
of the intermediate peaks became enveloped in fog
banks at the same time, while the cirri stretched
to near the zenith. The wind was then from the
westward, and the atmosphere humid, under the in-
fluence of which the lower strata of clouds increased
in number and density, and the sun continued
invisible until after the eclipse had made consider-
able progress. By half-past six all the fog-banks
to the north and west were drifting towards the
valley of Olmos, and at seven there was no portion
of the sky entirely unclouded. Whenever the sun
became momentarily visible during that period the
cusps could not be satisfactorily seen because of the
masses of vapour continuously rolling across its
disc. At about a quarter past seven there was a
striking change, the whole mass of cumuli to the
eastward was lifted towards the zenith, leaving
that portion of the sky clear, and it was only by
close examination that a delicate film of vapour
could be detected between them and the sun. At
this period the general light did not greatly differ
in intensity from that of the moon when nearly full,
though its colour resembled more that from burn-
ing spirit than that of the sun. Both intensity
and colour changed under the feeble and gloomy
illumination with perceptible rapidity, and for a
minute before the first internal contact of the limbs
the hills near appeared of a black hue.
At from 12 to 15 seconds before the beginning of
totality the entire lime, then perhaps 35 deg. in
extent, broke up into masses of unequal length,
showing detached portions wholly separated from
the rest by dark lines. Within the ten following
seconds the remaining visible fragments had be-
come brilliant globules of nearly equal size, which
differed from Baily's beads, as observed by Gilliss
during the annular eclipse of September, 1838, by
the darker spaces which separated them from one
another.
When the total obscuration took place, at nearly
31 minutes past seven, four masses of luminous
clouds became immediately visible at as many posi-
tions of the lunar circumference. The observer re-
moved the screen of glass from his telescope, and in