The Sun.
London, England, 1847-04-03 00:00:00

THE NEW PLANET.

The Syndicate appointed to visit the Observatory beg
to submit to the Senate the following Statement of Ob-
servations made by Professor Challis on the New Planet,
in continuation of those described in his former report,
and also of the results deduced from them by Mr. Adams
respecting the elements of the planet's orbit.
H. PHILPOTT, Vice-Chancellor.
JOHN GRAHAM. GEORGE PEACOCK.
B. CHAPMAN. JAMES CARTMELL.
W. WHEWELL, CHAS. W. GOODWIN.
JOSHUA KING. G. G. STOKES.
SECOND REPORT OF PROCEEDINGS IN THE
OBSERVATORY RELATING TO THE NEW
PLANET (NEPTUNE).
In conformity with a wish expressed by the Vice-
Chancellor and the Observatory Syndicate, at their ordi-
nary terminal meeting, held on March 15, I propose in
this report to carry on, for the information of members
of the Senate, the account of proceedings in the Ob-
servatory relative to the new planet, a first report of
which was made on Dec. 12 of last year. The theoretical
grounds on which a search for the planet was instituted,
the manner in which the search was conducted, and the
degree of success that attended it, were stated in the
former report, which brought the history of proceedings
down to the date. at which the planet was discovered. I
have now to give an account of the subsequent observa-
tions both of its position in the heavens and of its
physical appearance, and to state the results respecting
the orbit, which have been deduced from :he observations
by calculation.
A regular series of observations of the planet was
commenced on October 3, 1846, and continued at all
available opportunities, partly with the meridian instru-
ments, and partly with the Northumberland Equatoreal,
to December 4, seon after which the planet became too
faint to observe on the meridian on account of daylight.
The observations were subsequently carried on with the
Equatoreal to January 15. The series was much inter-
rupted by cloudy weather, particularly in the months of
December and January. On the whole I have obtained
28 positions of the planet with the meridian instruments,
and 25 positions with the Northumberland Equatoreal
by means of 92 differential observations of Right Ascen-
sion, and as many of North Polar Distance. The Equa-
toreal measures were all referred to the same star, No.
7,648 of the British Association Catalogue, the exact
place of which was determined by sixteen observa-
tions with the Transit, and eight observations with
the Mural Circle. I have reason to think that the
positions obtained with the Equatoreal are entitled to
very nearly the same weight as those obtained on the
meridian. All the above observations I have com-
pletely reduced, and have placed the results at the dis•
posal of Mr. Adams for deducing elements of the planet's
orbit.

On January 12, I had for the first time a distinct im-
pression that the planet was surrounded by a ring.
The appearance noticed was such as would be pre-
sented by a ring like that of Saturn, situated with
its plane very oblique to the direction of vision. I
felt convinced that the observed elongation could
not be attributed to atmospheric refraction, or
to any irregular action on the pencils of light,
because when the object was seen most steadily I dis-
tinctly perceived a symmetrical form. My assistant, Mr.
Morgan, being requested to pay particular attention to
the appearance of the planet, gave the same direction of
the axis of elongation as that in which it appeared to
me. I saw the ring again on the evening of Jan. 14.
In my note-book I remark, The ring is very apparent
with a power of 215, in a field considerably illumined
by lamp-light. Its brightness seems a qual to that of the
planet itself.' On that evening, Mr. Morgan, at my re-
quest, made a drawing of the form, which on comparison
coincided very closely with the drawing made inde-
pendently by myself. The ratio of the diameter of the
ring to that of the planet, as measured from the draw-
ings, is about that of 3to 2. The angle made by the
axis of the ring with a parallel declination, in the south
preceding or north following quarter, I estimated at 600.
13y a measurement taken with a position circle on Jan.
15, under very unfavourable circumstance&, this angle
was found to be 65°. lam unable to account entirely
for my not having noticed the ring at an earlier period
of the observations. It may, however, be said that an
appearance like this, which it is difficult to recognise
except in a good state of the atmosphere, might for a
long time escape detection, if not expressly and re-
peatedly looked for. To force itself on the attention, it
would require to be seen under extremely favourable
circumstances. Previous to the observations in Janu-
ary, the planet had been hid for more than three weeks
by clouds. The evenings of Jan. 12 and 14 were par-
ticularly good, and the planet was at first looked at in
strong twilight. Under very similar circumstances I
have twice seen, with the Northumberland telescope, the
second division of Saturn's ring.
I communicated to Mr. Lassell, of Liverpool, who was
the first to suspect the existence of a ring, my observa-
tions upon it, accompanied with a drawing; and I have
received from him in return a drawing of the appearance
presented in his twenty feet reflector, closely resembling
mine, both as to the form and the position of the ring.
Mr. Lassell writes, " I cannot refuse to consider that
your observation puts beyond reasonable doubt the
reality of mine." In this conclusion I concur, and ac-
cordingly in communications to the Royal Astronomical
Society, and to Schumacher's Astronamische Nachrich-
kn, containing my reduced observation:, I have ven-
tured to express my conviction of the existence of a
ring.

By micrometer measures taken with the Northumber-
land telescope, I find the apparent diameter of the
body of the planet to be very nearly 3 seconds.
The above account includes all the observations on the
planet I could obtain before its disappearance in the solar
rays. By the kindness of Mr. Adams lam able to add
some particulars respecting its orbit, which he has de-
rived by calculation from the reduced places with which
I furnished him. As was stated in tho former report,
Mr. Adams calculated first approximations to the ele-
ments, by employing the places I obtained on August 4
and August 12, in the course of searching for the pla-
net, with observations since the discovery extending to
October 13. For the sake of comparison with the se-
cond approximation, I now give the first results.
Heliocentric Longitude 326.39 Aug. 4, 1846.
Longitude of the Descending Node 309.41
Inclination of the Orbit
Distance of the Planet from the Sun 30.05

In calculating the following second approximations
Mr. Adams used the mean of the two places of August
as a single place, and of the others he selected nine
which seemed to be the best determined, and which were
separated by convenient intervals. All the results are
calculated for the epoch of 1846, Aug. 8,0. mean timo at
Greenwich.

Heliocentric Longitude of the Planet re-
ferred to the mean Equirr.,x of 1847,0 326.41.12,3
Heliocentric motion in Longitude in 100
days
Heliocentric Latitude South
Change of Heliocentric Latitude in 100 days 1. 4,44
Longitude of the Descending Node 3lO. 3.44,0
inclination of the Orbit 1.46.49,1
Distance of the Planet from the Sun
Half the Latus Rectum of the Orbit

The first position on which the above results depend,
that of Aug. 4, was obtained 16 days before the planet
was in opposition, and the last position, that of Jan.
15, 32 days before it was in conjunction. The great
variation of the planet's elongation from the sun in this
interval, is favourable to the correctness of the above
determinations, which, although they cannot pre-
tend to extreme accuracy on account of the short
period over which the observations extend, are yet
entitled to considerable weight. Mr. Adams has, in
fact, calculated the probable errors of the above re-
sults by supposing each observation of Right Ascen-
sion or of North Polar Distance to be liable to an error
of three seconds, and he finds that there is little probabi-
lity of their receiving any great amount of correetion by
taking account of future observations. It may be re-
marked that the first and second approximations do not
at
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than it would have been if it depended solely on obser-
vations made since the discovery of the planet.
The calculations gave 59 min. 8 sec. for the planet's
11.1iocentric motion from August 4 to January 15.
This is so small an arc that it is not possible to deduce
with any degree of certainty those elements, the deter-
mination of which depend); on change of the heliocentric
distance. Mr. Adams has, however, discussed the ob-
servations with this object in view, and has obtained
certain limiting results, which, as possessing considerable
interest, I here subjoin. '
The eccentricity of the orbit cannot exceed 0.18.
The most probable value is 0.06, which differs but little
from the eccentricities of the orbits of Jupiter, Saturn,
and Uranus.

The most probable longitude of perihelion is 49 dog.
58 min., and the probable true anomaly 276 deg. 43
rain., according to which the planet is near the extremity
of the latus rectum, and is descending towards perihelion.
These results are extremely uncertain.
The mean distance is 30, 35, with a probable error of
0,25 ; and the corresponding sidereal period is 167
years, with a probable error of about two years. It is
remarkable that the periodic time is very nearly double
that of Uranus ; so that these two bodies will offer an
instance of mutual perturbations of large amount, differ-
ing in character from those of the other planets, but
analogous to the mutual perturbations of the first and
second and second and third satellites of Jupiter.
According to Bode's law of the planetary distances,
the mean distance of the new planet should be nearly
35. The actual mean distance differs so much from
this, that we are compelled to conclude that this sin-
gular law, which holds with reference to the other
planets, fails in this instance.
Since the apparent diameter of the new planet is to
that of Uranus nearly in the ratio of 2 to 4, according to
the foregoing determination of the distance its bulk is to
that of Uranus in the ratio of 8 to 5.
The above is the sum of the results derivable from the
first series of observatiohs. For further and more
exact information we mud wait till the planet emerges
from the solar rays. Before concluding this report, I
am desirous of saying a few words respecting the name
of the planet. I recently had the satisfaction of re-
ceivingtion read by him at the general annual meeting
of
the Se
mtryu v
of 3 the
Sciences copy of communicaf
the
Impeiro
iam l
of
St.
rPetersburg
on Dec. 29, in which he states the reasons that
induced himself and the other Poulkova astronomers
to adhere to the name of Neptune, which name was
6;" Proposed by the French Board of Longitude,
:re ort. lyafter the discovery of the planet, these reasons
thus briefly expressed note
in a addressed to me per-
sonally:_' The Poul
kova astronomers have resolued to
maintain the name
name of L of Neptune, in the opinion that the
and against e
rwould be against the accepted analogy,
denied that 11 historical truth, as it cannot be
oretical discove'rer Adamso has been the first the-
m) happy as to that body, though not
effect •
A direct result of