The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1874-06-30
lFram che Baltimore American, 23d'l
Tysa Hra usit of Venus.

HE HEHuSts Va
Every bow in tie public schools who is
moderately well advanced in astronomy has
n toierably ,ciesr.ss,ea of the solar system. 1t
is represented to HIM with the sun as CEN
ire around which seven Or eight planets are
whi1lirg in circles, Of which there Is one 70
each planet, and that these circles are distant
from the sun in various deSrees-tnat OF
Mercury, or perhaps the prob!ematlc vulcan,
being the nearest, and Neptune the IartheSt.
:. But the fat is that the planets move in
elIjrses rather than in circles, and that the
elopcaiion Of the paths upon which they
travel will, at certain stated times, cause
them 10 move directly across portion OF the
SIMS orb. Such a movement is called the
transit of planet. For the purposes Of
observation from the earth the transit OF We
ms is the only one that is OF any practical
7,se. In the eighteenth century French
astronomer, NJ. Delambre, discovered star
very close TO the sun, which he has set down
as planet and given the name of Vulcan,
lint lis existence is doubtful. Next to 1t in
neurness comes Mercury, but it rey0lyes so
close 10 the central body that it is very rarely
seen with the naked eye in our latitude.
There have been attempts to take obServa-
tions of lis transit, but they have always
resulted in futures. Next comes Venus, and
then the Earth. the other planets being still
farther distant from the sun than that
which we inhabit. Of their transits we,
of course, know nothing, because
they do not cross the disc OF the
sun within our range OF observation.
But for astronomical calculations, the transit
of Venus is the great event to students upon
orr world. These transits have acquired
immense interest and Importance from the
j.tn hr " irht q sIln's
distance from the earth can be determined
with far greater precision than by any other
known method. Venus revolveS in an orbit
Within that Of the earth, and. next to the
sun and moon, is the most brilliant object in
the firrnameut visible to us. In the last cen.
fury astronomers perceived the Importance
o. observing her transit across the sun, and
Wien il took place in 1863 there were fifty
nine stations established in the various local
tiles from which the phenomenon was vlSl-
Bile. neatly all the Governments of Europe
8 ndipg out expeditions to take observations.
The atmospheric conditions were highly
favorable. and excellent views were Oh
tained: but the detects of the instruments
then in use and the faultinesS OF the calcutta
tions led to a wide divergence in the estl-
mates of the distance Of the earth from the
sun. The magnitude OF Venus is nearly
equal To- that of the earth, and its intense
lustre dazzles the eye and aggravates the OPP
teal defects of the instruments used. These
difficulties interiered greatly with the o5ser-
walton made in 1TG9; but there was another
and greater obstacle not unprecedented before
the expedition started out. This was as TO
the precise moment of the movement Of the
plauet across the sun-whether it should be
taken when the outer edges OF each hinged
Lao orb
departure could be precisely per-
ceiyed. Que expedition made calcula-
tions on one basis and another on the
other. 50 that when they were reckoned up
the distance between the earth and the SUN
was figured up at al3 the way from 81 800 $40
miles 10 Eos, 9S4 $50 miles. Such diverse fig
urcs were OF little Use TO students, and about
the year Sas2 the iaEaous German astrono-
mer EucEc, took hold Of them aud after
working them up fixed the proper distance
at 90, 2I4, coo miles. This was held to be the
correct standard until 1854 Hansen over
hauled the calculations and presented VI ,6o9,
900 niles as the result. Various other as:ron.
.olners worked mp the problem until 1t was
fixed by genac2s consent at 92,000,0 200 o.
miles in rounG! ,nambcrs. sWd if these figures
are WONG the world looks to the ob>erva.
lions 70 be anasle aext Boae,mber 10 correct
them. There is curious coincidence il
the fact, Us evolved by Professor Smyth, that
the distance ROW recorded ID precisely that
of the dimeHfiOEal features of the great
Dvramid, q DEMONSTRATION that many
OF THE illustrations now negarded Us
recent acquisitions OF astronomical science
WeEe kaown to the architects or that most
remarkable strneture. The linz of differ
enee between ancient as.roOgy :sa1 modern
astronomy is indeed scarcely perneRibe, and
in studying the work done centuries ago we
Iaunst but marvel ut the results achieved by
the scientists of the Oldea time, sHGtwiti.
standing tlat they W.ege SO aa iXcd with magic
and mysticism. The loiuutencss Of she work
OF the scholars &lo racastaS the hs4EeS OF
.the obseENations Of 1869 nlay be estimated
wheB K Is stated, As Sir John Uerscbalt says,
that the corrections correspond 10 tte:appa.
rent breadth I'd Il lnsna hair one bHndred
and faienty :Gse feet distant, or u sovereign
eight miles aWas. Aad it is ails2l refinement
OF science upon (which sre now expect 10 INA.
prove.
Tie tranSit OF Venus. " bich takes place liza
Deoes@ Der ateSt, is the first siAce that ss't
17L9. With the faults OF preyiaaAs obserSaL
tions u guides, sad tae pe!seetionof Instru-
Inents that has 4ean recently achieved, it Is
supposed That We Shalt now .appneach very
w 9tSOf6tC AAh 'S~S"'S
will not be visible in those parts OF the
world where it .cohld he most easily OBJ
served. 1t giH be Visible in vafiaes parts
OF the extreme northern hemisphere, but
the most faroratIe station will be fur away |
in the South. Dir. Proctor, in bis s. dnsra Ole |
work, gays that for the observation OF q
transit which occurs in December the !
weather is most likely to be good in the
hemisphere aud bad i'll the north
erp. If the atmospheric coalitions were
equally favorable in each the work
would be greatly simpHfed. But as
1T is, the most important stations Will
tie In the distant South, and it IL 10 these
points that the various Governments are
sending the msiority ut their expeditions.
Russia alone Confines the work Of her seie,rt-
lists to the North, having established u chail,
Of posts of observation across Siberia: hut
other Goyernmentsare looking in the other ;.
direction. The Fo!ynesian Islands, in thei
South Sea, will be most favorable stations,
and to them the United States, Great Britain.
France, and Germany are sending the greater
lumber OF their details for observation. The
;gatara, which sailed The other day from
few York, will land her frst party at the
'rOzet Islands. These are q group OF four )
mali barren islands In tue Indian Ocean,
bout fifteen hundred miles southeast OF :
10 Cape OF Good Hope. From thence
% ship Hiu proceed to Kergueleh /
Z r