, 1869-08-30

While, however, TOT purposes OF mere curiosity,
the phenomenon can be Etewed from any AelecteA
spot on large proportion Of the ea1;hd Srflacc,
there are teanY hut lew cl1kru11 Ir,.4ttus k.vaa
which astronomers can note the eyeut 10 adyau-
tase. It u He known that the great object Aimed
at vii! be al accurate determination ol the
parallax Of the planet, or the angular
dlnerence IL her position 1:::sa respect 10
the xun, as viewed from different points
oa the earth's surface. The maximum dtsptace-
mcnt will evidently BE- at those points on the globe
hostzon and thelr oppositcs, corresponding to the
position Of tito planet the SUMS limb, az ADORE
gtren. The anounr Of displacement Will decrease
in proportion 10 the costnc OF this distance from
these stations
The following rotuts hare been indicated by
Professor Atrey the best for observing stations:
For observing the HETess as accelerated b5 par
allax-0whyhee; factor Of pa1allax, o.9a: suns
elevation, two hours Marquesas: factor, u;
Ruu's elevation, two hours. Western Aienttan
Islands: factnr ca: sun Is degrees high 1t Is cx-
pecteA that these stations Will be occupied BY the
English. French and Kussiaus, in the order
NAMED.
For observing the iugtess as retar,Ied by pas-
allax-heEgue!en's lsland: factor, 0.o1; sun Is
degrees high. Crozeta Island: factor. o.os; sun
10 degrees high. Rodriguez and Maaritlus;
Madras: factor, 0.47 Is; and Bombay: factor,
Oh. All but the twu LAST named would need OBJ
longitude, and the factors OF pasallax for these
two are small
Fur observing The egress as accelerated by
raraliax-the stations in the order Of merit are
the Auckland Islands; Canterbury, Wellington
and Auckland, in New Zealaud; with factors
tauEtrR from 0.s3 to OF; Norfolk Island {o.6s),
md Melbourne and Sydney to.6,. The Southern
Continent would be a nrst-class place, but II 10
cousidcfed Al practically inaccessible.
For observing the eg7ess a. retarded By paral-
la1, the stations aEe almost entirely In Rus.!s
and Turkish territory, with no fac,os less than
e.sl. Unsl, Ofsk, Astrathan, Elzeroum, Alep-
po. and Smyrna are indicated a. stations hasing
the srn sufficiently high; and Constantlnopc,
Odessa, Athens, Tobolsk, Perm, kazsu, and Ehar-
koy As having the son low, while he will be On
the horizon at MOSCOW. These stations will prob
ahly be attended to By the Russ!an aad Turkish
Governments. Alexatdrta viii be attended to by
thc British.
Some Of these stations are selected with refer
cnce to another transit Of the same planet, which
will occur IN 1852, aud be available for astrononi.
chi observation In the Eastern Suites, Cauatas,
West Indies and Central America 1t mus, not
be Inferred however, from this, that transit OF
Venus Is an event Of or,1nat5 occurrence. The
phenomenon really Il double onc-shere are two
transs eight years asundef, hut there Is an iutcr
mi Of more than century between two consetu.
lses. the nc1s after that Of 1854 will occur In the
year eD4.
Fer each OF these stations transit Instrument,
Al a1taxluuth, clock, and several thermometers
and telescopes Will bc required In addition to pho
togrRrhc apparatus An attempt will also pruba-
biz be made TO establish another station on the
Southern Continent, Ia east longitude l05 de 3.ees.
The approaching runs.t l. Of great sc!cuttnc
interest, As natrouomc1s expect to bc 2ble to
a ~ q An1rt mr. ha
| tr means Of the observations then made The
mean distance was estimated ut nbout aa 365, 900
OF miles IRON the observations made the trnn-
ait Of l769 bnt reduction Of series Of obscr-
vutions on the neridAna1 paEs28cs Of the moon at
! Greenwich, published IN 1sch showed that this
| assumed distance waa necessarily too great, AMI
some asIrononers hare evcu gpne 80 far ~ TO
charge that the times Of contact given hy Father
| Hell ~ observed BY him at WAsdhus, \; the
northeast extremity o! Norway. were forsc.eL
| This was almost the only nnc Of the numerous
I statlons sclettcd at which the view MAS nn-
ooscurctl by clouds, anl tue figures obtained irou
| that station had most TO 10 In the estat-
lHhment o! thc received Eatnc OF the distance,
II IL difficult 10 understand what not!sc this
cccltslAstlc could have In Nlf1tly sa!sl'JlnR tho
fecogI: Int there il little doubt that he did 10, ~
notebook was found, IN tS5k among his manu-
scripts q: y!cDns which Is heltcYed to hc tho one
used ~ him 1t wardhus. The principal ngures
h.a ,rcn crp .eJ - 4. n In ccoct a1ty il,cp,hr
~. ,,,n.,,s n, N, rnoon .,rc,dx ,r,,,rn, IN
| -..oast.-o,,.. -, ~. .sa..,.s ,,rts
~ =. sn,,.,,,s., ~. .,,.,,,..,, =,
u."a' ~ 80. -. ,.st ."s s,,.uos ~
that tho mean distance Of TIC earth rum tho sna
| Wa hot @1"'e WA" t'.'"''"o n!''ep' 4AA> 's'
hot VIZ Annou"eea " tFo'estoF Hansca
5utSequcnuy ~ Net1lcs, tae sFcaca ~.
trpnoMrf HofA. male eef!cs Of careful
computations Of Inc motions Of tho piAaeta
Venus and Mari, and catno 70 tho conclusion thai