Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1872-08-14

LETTER FROM FATHER SECcHI, OF TIE ROM.
OBSERVATORY.


OBSERVATORY.
Father Secchi, writing from the observa-
tory of the College of Jesuits, Rome, July 10,
says:
The great spots on the face of the sun had
entirely disappeared for some time past, but
on July beautiful and very large one was
distinctly visible even with the naked eye. 1t
presented some remarkable variations. Very
small at first and consisting of little specks, 1t
gradually increased in size until it attained the
dimension of mn a sec. in diamenter. But
its size was not It's principal distinction. 1t
was remarkable as specimen for solar analysis,
as it DISPLAYED In its centre some violent erup-
tions of hydrogen gas directly visible in the
centre of few nuclei, occasioned by the revers-
ing of the rays Of this gas, as also in those that
surround and cross them. Dense vapors Of
sodium, magnesium, chalk, and iron were
spread over its vast area In such quantities that
never remember to have witnessed the like
before All this shows renewed activity in
these regions which had of late appeared to be
entirely tranquil The motion of the rays was
confused and the entire matter convused in
every sense. 1t is impossible, without the aid
Of instruments, to give person at a distance
any idea of the phenomenon.
The spot in question was in the central
hemisphere, and gradually inclined to the
eastern extremity OF the suns disk. Another
striking sign, and a contemporaneouS one,
was the existence of violent eruption observ-
ed on the extreme edge of the sun at few de-
grees distance from the most eastern limit Of
the spot Is deg. from east to north). The
morning was cloudy, and | was unable to
make drawing of the sun until about forty
minutes past two iu the afternoon, and at that
time I could only perceive a small jet of very
bright fame alongside of great one of hy
drogen gas. Having observed very carefully
the round of the entire surface of the sun, |
was surprised on returning to the same spot,
at about thirty minutes past three, to notice
lively eruption, but not by any means an elevat-
ed one. At half.past three it was about fifty
seconds but its vivacity was extreme. 1t con-
sisted of a dense and splendid cloud, sustained
by an infinite number OF rays, proceeding from
the edge of the solar disk This cloud was
formed, besides hydrogen, of an unknown sub
stance, which gives on the spectroscope VIVID
ray near the centre Of the two Is and Y, so
that the reflection was entirely formed OF this
new kind of ray. The rays of sodium, mag
nesium and iron appeared as 1t were, topsy-
turvey, so that these rays we're In abundance,
to say nothing of those of the hydrogen.
The movements and changes were SO rapid
as to be easily perceived by the naked eye. At
). ID tney attalucu CtlG clCVdtiou VI
chiliometres that is about ten terrestrial diam
eters, and their elevation was preserved pretty
nearly all the time the phenomenon lasted
The lines seemed to be multiplied, and to
form groups which, at times, renamed
stationary, and then fickered too and tro.-
They looked to me like the legs OF In
sccts moving about. They were really form:
ed of dense rays, which now united and
now separated, so that they were always IN
motion. At 4:30 the mass began to diminish
in intensity, and then | was able to recognize
its internal organization. The rays now assumed
the appearance Of acanthus leaves surrounding
Corinthan capital and presented a most
beautiful and wonderful sight. At o'clock
the eruption again became intense, covering
over ten solar degrees and as the ex.
tension was greater than heretofore so the
height increased to the double of what lt'had
already attained. At $50 it diminished, and
at o clock was entirely extlngulshed, SO that
the special rays appeared less brilliant than
those of the ordinary hydrogen.
tried my best to discover any magnetic IN
fuence during the eruption, but not until 1870
did | notice anything of the kind; at that hour
considerable magnetic influence was manifested,
and this morning it was extremely. violent
July l0) Whether this has anything to 40
with the condition of the sun, or is occasloned
by the violent storms announced ny Chc leio-
graph, cannot say. This morning the large
spot already mentioned as being IN proximity
of the eruption has entirely disappeared.
Another eruption is also noticed this morning
near the last, which has almost entirely ceased.
As astronomers are much occupied by these
phenomena Of solar spots, think it my duty
to inform them of what have witnessed, The
nvariable apparition of spots in vicinity OF solar
eruptions, leads me to conclude that they are :
produced by the said eruptions, and consist OF
dense masses of vapor, which have, been sent
up by the eruption, and have refallen on the
surface of the sun. This, Of course, is only
theory, but it may prove Of use.
p. A. SEcCHI
From the Roman Observatory, Jug ~, 1917
prp,r-n, ,r1oN oE THE SrN's SURFACE