Evening journal., 1899-07-01

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tion OF the principles Of analytical me-
chanics. all Of which have lent their
powerful aid in making astronomy one
Of the most perfect in the whole array
OF sciences. Photography. especially,
has been Of inestimablo beneat for
astronomical observations and pro-
tloed results that might not have been
found by any other method. Professor
Pickering. of Harvard University, has
been one OF those who paid much at
tention TO observations by means Of
photography, especially IN observations
Of the satellites OF Jupiter Photog-
raphy has been extensively applied to
observations of the moon. the nebular,
The solar corona, the solar spots, and
the transit of Venus. In making charts
OF the stars, which for many purposes
are more convenient than mere cata-
logues, photography has played. and IS
destined 60 play, still greater part.
Quite recently very satisfactory re-
suits have been obtained by the aid Of
photography in determining the an
nual parallax Of stars.
On the 18th OF August, 1898. q new
planet was discovered by means Of
photography at the Urania Observa-
tory, IN Berlin. by Herr G. Wiu. The
same night 1t was also caught on a
Photographic plate by Charlois, of
Nice, but does not seem TO have been
detected on the plate until after the
announcement of Wits discovery.
Tho newly discovered planet was for
some time Professionally designated as
d. O., but is now called Eros. It was
so faint as easily TO escape notice, and
since its discovery has been detected on
at least 20 or 30 plates, made at Cam
bridge United States, and other places
before Witt sound IL. The eccentricity
Of the orbit OF Eros is extraordinarily
large, in consequence OF which there is
a great difference between its maxi
MUM and maximum distances from
the sun. It's aPhelion distance
is 16e3o5,OOO miles and its
lperihelion distance S1O4, 4,5Gl 600
miles, making the average distance
l35,4SS,O0O miles. while the average dis
tanoc Of Mars is 141.5OO.OOO miles, SO
that about half Of the orbit Of Eros Is
within that of Mars. 1t would not be
proper to say, as occasionally it has
been said, that the path Of Eros lies
within that Of Mars. The eccentricity
of the orbit is so considerable as to
make the planet approach within four.
teen millions Of miles Of our own path
laround the sun. The synodic period
of Eros. that is. the period between
two consecutive conjunctions or opposi.
tions is $40 days, even exceeding by 81
days that of Mars, which, before tn,
Z discovery Of Eros, enjoyed the distinc
e. ton of having the longest synodi,
E period Of all the planets. The most IA
I lvorable position for observation whicl
= a superior planet can have is wheI
;. opposition occurs near its perihelion
r since in this position the planet 4
e nearest to Us. In the case of Ero
d this, must have been in 1894 when ii
s stellar magnitude was about the sey
n enth, almost within naked-eye yisibil
o ity. This viii again happen in 1921
It and in that year astronomers will b
# enabled to provide more accurat
il value Of the suns distance than Ia
r been obtained by any other metho'
)fl Eros will then come within 100000
e. miles nearer the earth than Mars eve
be does and thus present a most favorab
X. position for observation. The siderei
In period Of Eros. within which it makl
n one complete revolution around q
to sun is 642.9s days, thus being
ye about "A days shorter than that
a Mars. Though the size Of Eros has n
been accurately determined, it is in q
'e- probability not exceeding 20 miles
Sc diameter.
Te- The principal consultations that W
re come to the meridian at about 9 o'clo
is in the July evenings are Scorpio. He
al cules and ODhiuchus. or all the
OF consultations of the zodiac Scorpio
ca indisputably the most brilliant The p