The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1900-05-26

with a special eyepiece TO reduce the
binding intensity of the suns image.
II is found to be covered with minute
granules much brighter than the back
ground on which they lie, presenting
! an appearance which has been likened
to snow1akes on white sheet. These
granules are bright incandescent
clouds. Though they occupy less than
one-half of the suns surface, they
radiate most OF its light.
CHEMICALS IN THE SUN.
The layer OF gas lying just over the
photosphere 20 depth of about 500
miles contains most of the elements
which produce the dark lines in the
solar spectrum, and Is for that reason
called the reversing layer. The spec
| trum of the reversing layer photo
| graphed in the absence of light from
the solar surface. as on the occasion OF
total eclipse of the sun, consists of
| bright lines, the dark lines reversed
Above the reversing layer Is the chro-
| mosphere, the suns atmosphere of
which the reversing layer is the lower
| lying strata The chromosphere ex-
| tends from 5000 to 10000 miles above
| the solar surface. 1t is composed prin-
cipally of hydrogen and helium. Seen
only on the occasion of a total eclipse
| it presents-to quote Professor Young
'the appearance OF a scarlet flame. not
composed OF horizontal sheets, but of
| upright fllaments. Its appearance has
been compared very accurately to n
prairie on fire" This, however, is not
to be understood to mean that COM
bustion takes place. The temperature
Is too high for that.
In the chromosphere are to be seen
! scarlet cloud-like objects suspended
$4,000 or $4,000 miles above the photo
sphere. with which they are generally
| connected by means of slender fla
ments. These are quiescent promi-
nences. They are masses of incandes-
cent gases, principally hydrogen and
helium. Other prominences are to be
seen which differ from the quiescent in
that they are much more brilliant and
active. They appear to be cast up from
the body Of the sun by an explosive.
or eruptive force, and hence are called
eruptive prominences. They contain
many other metals besides hydrogen.
At times they change with astonishing
rapidity, having been observed to move
with velocities Of 200 and $50 miles
| second.
Prominences are visible during
total eclipse of the sun with a tele-
scope. and occasionally even to the
naked eye, presenting the appearance
of crimson flames projecting from the
black disk of the moon. BY means OF
the spectroscope prominences may be
observed without an eclipse, and a
modified form of this instrument en-
aoles the astronomer to photograph
them.
THE CORONA.
On the occasion OF a total eclipse
there may be seen, and seen at that
time only, the silver bands and stream
ers OF the corona extending radically
from the sun. Photographic and vis-
ual observances of the corona are
among the most important that can be
made at total eclipse. "A compari-
son of accurate drawings with photo
| graphs of the corona shows that the
two are substantially the same in ap-
pearance. The latter has the advan-
! tage of furnishing a permanent and
accurate record not only of its general
appearance, but also of it's minute de-
tails, and may be studied at leisure
in the laboratory. The form and size
OF the corona, as we'll as it's bright
ness, change greatly. In general the
coronal streams are made up Of bands
and tilaments often strangely curved
and intertwined. Near the poles they
resemble tufts of threads sharply de-
fined. For the most part the length
of the streamers does not exceed the
suns radius, but at times some Of
them are seen to extend far out into
space, as was observed in the clear
air of Colorado at the eclipse of dS7S
where two of them were traced to a
distance Of 100000 miles. The spec
trum in the corona shows that it
shines partly by reflected sunlight and
partly by light emitted by the incan-
descent gasses which compose it,
among which are calcium, hydrogen
and a hitherto unknown gas called
coronium recently said to have been
discovered in Italy.
The corona is formed of matter
elected from the sun. Its substance
must be inconceivably rare, since
comets have passed through it with
out suffering a noticeable change in
their motion. All methods heretofore
tried for photographins or mapping
the corona without an eclipse have
failed because of the brightness of our
atmosphere.
TO MEASURE LIGHT.
Among the interesting observations
to be made at the coming eclipse will
be measurements of the intensity OF
the coronal light, the distribution of
the different gases in it by means Of
the spect-oscope, the heat it radiates.
the form of the coronal streamers ana
their variation in brightness at diff
ferent distances from the sun. Spec
troscopes will be used to photograph
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