New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1878-05-04
THE TRANSIT OF MERCURY.
,crpoyoMICAL EVENT.

,,ovnAy,s ASTRONOMICAL EVENT.
-,n,r,cTfox OF THE LATE Ne LIE I'M -
' rxKSowN BODY DISTURBING lhn ,'I-n,~o
~ OBSERVATIONS ODE MADE d. --,,,
hhh'O"- ~yxTrxsIyE PREPARATIONS FOX
CAREFUL WORK. y, .oI,o nlace
rS-o trorsit Of Mercury, which Will take p."oo
~, Monday MAY o., is an event VI , rrocision
.anonov II will be observed WIN uhu'",I ,ho late
"a care chiefly because OF quesuon o,er mart of
:, "a vo,rier That astronomer spent 'h' -. tracing
t u,e IN the study of the orbits OF inc rho changes
ont by means OF profound to diaerent bodies
h,ch are produced in the orbits as r. vas while en-
"hi0n -, - ocede from each other. IL va" ~ tbe
S e. his work. and after long 80 mat It's r-
80, q, Irranus that he was lea TO H' mon the theory
80 ooprse could only be eAP',, ~ odictiop NJ the
-. outs,de planet attracted IL 80 and the
that au 100 Of that outside planet " 49,
time and place :, in accordance with his
actual di'oo ,o,ever be regarded as ahonH
p"'Sos, trumphs OF science III 'no
TUG ~ HIS life, NJ. lie NerIle, 'a. A.,
Sshot similar conclusion respecting 'u' li'''o' .'
II, opalvsis led him declare that TIE ho'iom
enry Ills "' ,Ion ia GREATER than the action OF all
OF 'aoi0uls ,nts will explain. The presence OF one
'n ,o,orv bodies nearer TO the sun lhah IL -heI
VI n0ie ls,aato6 nv these celebrations But the goou
~: which led 10 the discovery Of NEPTUNE has nv,
"aIoIed as vet by finding an mira Mercuiin
planet ,.,,,p, ZACH OTHER.
r,o ,brase " motion Of perhelon is liAcl! ""pp."t
,antIv within some weeks, Iii statemen'S "oou' 'n'
-, The perihelon Is Of course The point Oh 'no
tr"h'1 ,bo plapet comes nearest TO the sun
-, notion of what is meant, may be got py cou'
,,o,,pg or imagining simple piece OF apparatus Au
,ron loon or elongated ring las suins ue"
cross the longest way The string then lorne tn'
TONG diameter OF an elpse The ring Is ald on 'Dc
and pin is driven through the suing lnto le '"o'
The position OF the pin is in one OF tne loci u 'HI
unse The min is TO represent the sun the eL'pIcai
,,on ring a planetary orbit; the ENDS OF the sulng
they are tied TO the ring the perihelion and aphe-
- wow a magnet may he dragged on the table 10
nresen The disturbing planet. Presently 1t causes the
,np 70 shift its position. The pin Will su remain at
,be focus Of the ellpse, and exercise restraint
,nvoreb the string; but the perihehon-one
,xtremity Of the ellipse-win change lis posi-
ZION ON the table, The astronomer wishes 10
~ in the case of Mercury, how much the pcrhelion
1 sbifed that he may calculate thcrefrom the place
nd nositon of the attractive but unknown neighDor
More exact facts about the movements OF Mercury must
No had before the alleged irregularities can be fuly de-
,-ined These facts may he best obtained by obsery-
h nrectse instants at which the planet the
1co Of the suns disk The transit VIII occupy more
an seven hours and will be visible in all parts of this
country The diagrams here given show three positions
Of tho sun and planet calculated for this city.
FIRST EXTERNAL CONTACT.
Uen apuroachng the sun, before the transit, Mercury
viii be invisible This will be understood when it is re
nembered that the planet, in different parts of its orbit
exhibits phases like the moon, according as It's bright
surface Is more or less turned toward Mercury APP
pears full when the opposite side OF tue sun from the
earth; Is in quadTature when apparently furthest one
side or the other from the SUM- but when approaching
the sun, ana between 1t and the earth, the
planet becomes a more and moro slender crescent
uptl all three bodies in line, when IL disappears
Is appearance in transit will therefore be dark spot
uDon the solar surface and its exterior contact Will first
he indicated by slight ndentatOD in the circular edge
OF the sun There two ways Of designating the place
Of this indentaton: o. it will be AS from the north
nOint toward the east OF following limb ;
I2J it will appear in this city ut u distance
Of 500 from the SUMS yertex. These technical
statements may be explained ms follows: The north.
pon Of the is approximately the place on the edge
that would be crossed by line drawn from the centre
OF the sun 10 the pOlc-sar; the exterior contact OF Mer
cury will take place As to the left OF that point III the
dsk of tho sun be bisected by plumbine, the places
where the line cuts the suns edge are the upper and
lower vereX and il this experiment be performed In
York the place OF exterior contact or Mercury VIII
he about sO to lett OF the uppervertex II witnessed
through an astronomical telescope (Which reverses the
place will be so TO the right Of the lower vertex. The
lime will he, in Washington four hours past ten in the
morning here, about sixteen minutes past ten There
4 little hope Of observing this feature Of the transit with
great precision.