, 1872-10-12
THE TRANSIT OF VENUS.

| THE TRANSIT OF VENUS.
Difficulties in thc Why OF Takin
| Cid Sol7s Picture
From TIC Washington Star.
a commission, consisting OF Rear Admiral I
F. Sands, Superintendent Of the United State
Naval Observatory. and Professors Henry. .Pie1c,
| NeWco1nb, and Hardness, Has appointed by Coz
gress to superintend the observations Of th
san- This rare end interesting phs
nomenon in astronomy will occ1
the year 1882: after which there viii be non
OF current interest The coming transit IL
| Decembec, however, occupies largely the atten'
! ton Of the scientific world The astronomer
Of Great Britain, Prussia, Russia, aaded by 1a1,s
grants Of money from their respective govern
uaents, have been engaged for more than yea
IN active preparation for the observation, Will
! in this country an appropriation has been mad
by Congress for fitting on. expeditions for th'
same purpose
| municatIon to Congress, this phenomenon WI
| afford our countryI1en peculiarly favorahle op
| portunity to exercise their inventive ingenuit,
!, IN the introduction Of improved modes Of OBJ
| ser1ation- Their successful introduction OF tTe
! OF the most important appliances in p1actica:
| astronomy photography and the
electro -chronograph, both Of which are non
] widely adoptedin Europe-their successful com.
| petition with Europeans in producing some ot
| and the rapid ADVANCES which practical astron:
I omy has made in the country within the last fen
! years. all WARRANT the belief that they can taks
leading position in making the observation in
question. :
But it seems that it is not SO easy task t.
! photograph the sun as it might seem to be. Old
Sol is as shy OF being 'took,'' pictorially,
as any mundane criminal Is OF having
his @'mug" figure in '*rogues' gallery
and, ike the class Of customers last named
he is apt to make faces and dis.ort his features
out Of recognition when the camera is applied
The difficulties in getting his picture arc sug-
gested rather yiyidly BY Dir rutherford, Of New
York. who has given much attention to solar
Commission for advice respecting the best meth
cd OF applying photography the determination
OF. the relative positions Of Venus and the SUE
during the transit Mr. Rutherford, in reply,
after pointing ont the requisite measures to be
taken, proceeds to say:
*sAfter the photographs have been obtsinea,
with all the precautions q careful foresight can
suggest. it is important that no reliance should
tnbe placed for precision upon the apparent OUT
line of the sun at any isolated point.s'
|. And he adds:
*.Perhaps yon viii be tempted to say. II
this be true, what reliance cso be placed
upon the results Of Photographic I should
answer thas the sun has no sharply defined
UQtt11tS, dfEA L0 Luz H3Gs put IN Ills Re9k
state is an irregular, seeth7ng, eyer-restless
object, utterly unit to be the starting point
for measures of precision; and that, while the
eye is confined II its attempts q. measures to-
Eome small part Of the suns limb, the photo
graph Of the whole sun can be placed upon tke
stage Of the micrometer and accurately centred
With reference to the average of the whole con-
tour, and thus escape tbs errors sure to be the
result OF n measures based upon local
{r fn CHI 4F
adn accurate measurements It's place should
he compared With the centre of the sun, and not
Tlth the limb"
Professor Newconb also, IN discussing the
meI1ts OF the two methods of observing the
transit, declares that s'recent regearches On the
physice1 constitution Of the sun lead to the sus-
picion that the atmosphere is subject to changes
Of level which might seriously impair the &C.
curacJ Of the result reduced from the most per-
feet observations Of contact" Professor n. put
it rather quietly about the changes Of level,
which impair the accuracy Of observation, but
according to another physicist, Professor Young,
Of Dartmouth College, these little ebulitions
sonetimes shoot ont from the 6un couple Of
burst Of solsr energy OF this kind that came IN
der his observation, remarkable for its sudden
ness and violence bis attention had been
directed for some tins toward an enormous pro-
Limb Of the sun, which had remained with little
change since the preceding noon The total
length Was about 10000 miles, and the
depth about 10000 After an absence
Of few minutes remarkable
change was observed by PTofea-
sor Young to hare taken piece in this object,
caused by its violent disruption during TINT Pc
rod. In place Of the quiet c1oud the space
above it was flied with floating debris. mass Of
detached vertical flanents in rapid motion;
some OF them having already reached q height Of
nearly one hundred Thousand miles, and still
rising, with motion almost imperceptihle to ths
eye, until in ten minutes the uppermost we're
more than tEo hundred Thousand miles above
the solar surface, shooting up at unparalleled
velocity Of one hundred and sixty miles per !
second
AS to the nature OF these solar protuberanccs |
there various theories. but the prevalent one
that Of Zollner-is that the soler philosophers j;
is an incandeacent liquid mnss of stratum, by !
ths weight Of which, various gases, especially t
hydrogen. are confined and compressed in the I
interior Of the sun at an ele7nted temperature, !!
and tha. these occasionally rise toward the sur !
face with great velocity, until they force them |
selves through With rapidity greater OF less, t
according to the depth from which they emerge. I
These aSS;tahons and erupt:ouB it is supposed, !
the protubera1ce- /