New-York tribune., 1873-01-28

FTs diagram s copy Of the one shown on the screen
and represents the apparent paths OF Venus across te
,uue disc during transit, as viewed from stations on
uposite sides of the earth The upper and dark circle
represents the planet from the Southern hem
sphere and the lower light circle the planet as seen
from the Northern. The shows the direction OF
She motoul
Prot Young described the manner in which the dis
tanoe could 6e ascertaned When the second diagram
was shown, Prof Young explained that was intended
20 show what the appearance would Oe az seen rom
northern station the earths surface say IN Japan or
KaInsehska The planet will strike the eastern side OF
the sums disk the northern edge and WIZ pass
o0uely along the two lower lines occupying about q
hours A. from Japan II will pass along the upper
of those dotted lines. AT any gwen moment the
pane as the southern station VIII be represented
Sy mat black SPOT At moment the edge of the
suu from the northern station would be represented
measure IN seconds the distance between the center OF
tba black spot and this rm and 10 do II with extreme
distance Of about 20 miles would be fatal 10 any
Oi the accuracy Of our present knowledge.
sTATIoHs IN BOTH HEHIsPHEREs.
TIE be regarded as seen from the sun the
when the planet strikes the disk OF the sum- pro
v1ded an observer earth at it's center AT that
moment suppose yourself transported 10 the sun looking
toward the earth This will show the apparent path OF
shadow Of Venus upon the earth The stations TO be
chosen for observation must be set around the edges OF
the world You want 10 he as far from the center OF the
earth ar possible There very good stations you see
Kamschatka, Siberia, China, and SIAM even into HIM
% aId must DO the Se can s sHd
tumber OF small islands 10 the Southern Ocean
M course during the four hours transit earth Will
furp around somewhat. You that Australia will
come nearer the edge of the map and the CONT
nenf Of Africa will then come into view and some few
s'st,oDs can be occupied in Northern Africa In The
I,alU however the stations VIII be indicated before
METHODS AND INSTRUMENTS EMPLOYED.
In measuring this distance there will be three different
uethods pursued The OldfashiOned way was TO note
when the planet strikes the sun, and when it It,
from which we may the number OF hours takes
10 pass across The disk Of the Thus al the northern
son VIC have the length OF the chord which II passes
inr the length of the chords II Is not dlhcnt 70
,ompute the distance between them. sT george H.
Airy the Astronomer Royal OF Lngiand, Is dsposea 70
fry mainly upon that method But there are giea uii.
trnltes with II. The main difficulty IL ihis; prlSh'
object looks % the eye larger than ts real sLe anu
ark body projected IT. OOks smaller tDan its reaI
aye The Consequence that this dark spot becOnos
distorted INTO peaTke form hanging upon the euge OF
tbe tuu by sort OF HgdmeDt which nnaly breaks ON
Aud N ~ difficult observe the moment wleD tney
lreak of 40 that 10 dfhcut 70 determine the precise
when the uanet cutters upon the suns dlsk 90
cUlt h that results OF the last IaDsli vert
very erroneous EDcke dedueed from them distance
which turns out 10 millions OF miles TOO great
AbotheF mefbod which wall be used mainly Dy the
German ASTRONOMER IL 10 measure the position VI Lbs
~ ume an reference 10 tie edRes OF tht
sess elss ~ mesns vi te heLoiastsf' Nv 'oshpsp' w