Evening star. [volume] (Washington, D.C.) 1854-1972, 1872-09-25
Largest Circulation in the District
Reading Matter on Every Page.
WASHINGTON CITY:
"WEDNESDAY. September Is, is72.
DIFFICULTIES In the Way of Taking OLD
sol n Picture

comm >siOn, consisting of Rear Admiral
b. +. SANS, superintendent L. 3. Naval OBJ
servstory, and Professors Henry, PIERCE, New
comb and darkness, was appointed By Congress
to supeTintsnd the observations OF the coming
transit OF Venus acroSs the disk OF the sun
This rare and interesting phenomenon in astrOn-
Omy will occur on December S, 1874. and again
n the year 1852; after which. there VIII be none
until the year 2fOf, an event too far ahead to b,
Of current interest TO the readers OF THE STAR.
The coming transit in December, however, &C.
CT pies largely the attention of the scientific
weird. The astronomers OF Great Britain, Prus-
ia and Russia, aided b. large grants of money
from their respective governments, have been
engaged for more than ayear in active prepare
ton ter The observation, while in this country
AN appropriation has been made by Congress
for hitting ont expeditions for the same purpose
As POINTED cut by Admiral Sands in his commu-
niostiCn to Congress, this phenomenon will afford
our cOEn:rymen peculiarly favorable Oppor-
tunty to exercise their inventive ingenuity in
the introduction OF improved modes of observa-
ton. Their successful introduction OF two OF
the most important appliances in practical
astronomy astronomical photography and the
electro chTOnograpn, both OF which are now
widely adopted in Europe their successful
competition with Europeans In producing some
OF the finest classes OF astronomical instr uments
Omy has made in this country within the last
few years, all warrant the belief that they can
take q leading position in making the observa-
tons in question.
But il seems that ID is not so easy a task to
photograph the sun a. il might seem to be. Old
Sol Is as shy of being took" pictorially, as any
mundane criminal is of having his "muy" figure
in "KOgues' gallery" and like the class of
customers Just named, he is apt to make faces
and distort his features out Of recognition when
the camera is applied. The difficulties In get
ting bis picture are suggested rather wildly by
Mr. Rutherfurd, OF New York, who has given
much attention 70 solar photography, and who
was applied to by the commission for advice re-
specting the best method Of applying photo
graphy TO the determin alton OF the relative POI
sitions % Venus and the Sun during the transit.
Mr.. Rutherfurd in reply, after pointing out the
requisite Measures 70 De taken. proceeds to say:
"After the photographs have been obtained,
with All tie PRECAUTIONS careful foresight can
suggest, u = import ant that no reliance should
be placed for precision upon the apparent out
line OF the sun az any Isolated point
And be adds;
" Perhaps YOU viii be tempted TO say, If this
he tue, what reliance can be placed upon the
results of photography? / should answer, that
tie sun has no sharply defined outline, even 10
the eye, bat, in it, best state, is an irregular,
seethinc, ever-restless object utterly unit to be
the starting point for measures OF precision; and
that, while the eve il confined in its attempts ar
measures. 70 some small part of the suns limb,
the photograph of the whole sun can be placed
upon the stage Of the micrOmeter, and accur-
ately CeEteTed with reference to the average of
the whole contour, and thus escape the errors
tuTe 10 b. the result OF measures based upon
local biseCtiOnS. The image OF Venus Ought ID
lie sharp and capable OF easy and accurate meas
urements. is place should be compared with
the center OF the sun, and not withthe limb"
Prot. Newcomb, also, in discussing the merits
OF the two methods Of observing the transit, de-
clare= that recent researches on the physical
constitution Of the sun lead to the suspicion that
the IEOtosphere Is subject to changes OF level
which might seriously impair the accuracy of
the results Geduced from the most perfect obser-
yatiOuS of contact" Prof. y. puts il rather
quietly about the changes of level" which
impair the accuracy OF observation, but, accord
ing TO another physicist, Prof. Young, Of
Dartmouth College, these little ebuIl-
lions sometimes shoot out from the sun
a couple of hundred thousand miles. He
describes an outbarst OF solar energy
Of this Kind that came under his observation,
remarkable Tor its suGdenness and violence. His
attention had been Greeted for some time to-
ward an enormous protuberanee OF hydrogen
cloud Oh the eastern limb OF the sun, which had
remained with little change since the precedin,
noon. The total length was about one hundred
thousand miles and depth about forty thousand
Aiter al absence OF a few minutes a remarkable
change was Observed by Professor Young to
have taken place in this object caused BY its
violent disruption during that period. In place
OF the quiet cloud, the space above IT was filed
with floating debris, a mass OF detached vertical
haments in rapid motion; some OF them having
already reached height OF nearly one hundred
thousand miles and still rising, with a motion
almost perceptible to the eye, until in ten min
utes the uppermost were more than two hum
dred thousand miles above the solar surface.
shooting up at the unparalleled velocity of one
hundred and sixty miles per second.
As 10 the nature OF these solar protuberances
there axe various theories, but the prevalent
one-ttat Of ZOllner-is that the solar photo
sphere Il an incandescent liquid mass or
stratum, by the weight of which various gases
especially hydrogen, are confined and COM
pressed IL he interior OF the sun AT an elevated
temperature, and that these occasionally rise
towards the surface with great velocity until
they force themselves through with a rapidity
greater CT less according to the depth from
which they emerge. These agitations and erup-
tcEs, it Is supposed, Constitute the protuber-
anCes.