Scientific American Supplement, No. 303, October 22, 1881Various
Science
Scientific American Supplement, No. 303, October 22, 1881
Various
Science -- Periodicals
[Footnote 1: "Monthly Notices K. A. S.," January, 1873.]
"1870, Jan. 25, 11h. to 12h. in clear and tolerably steady air; power
132 showed that the disk was not uniform. With powers 202 and 3.0, two
round, bright spots were perceived, not quite crossing the center but a
little nearer to the eastern side of the planet, the position angle of a
line passing through their centers being about 20° and 200--ellipticity
of Uranus seemed obvious, the major axis lying parallel to the line of
the spots.
"Jan. 27, 10h. to 10½h.; some fog, and definition not good, but the
appearance of the spots was almost exactly the same as on the 25th."
On March 19 glimpses were obtained of a light streak and two spots.
On April 1, 4, 6, and 8, a luminous zone was seen on the disk, and
in February and March, 1872, when observations were resumed, certain
regions were noted brighter than others, and underwent changes
indicating the rotation of the planet in a similar direction to that
derived from the results obtained in 1870. Mr. Buffham points out that,
if this is admitted, then the plane of the planet's equator is not
coincident with the plane of the orbits of the satellites. Nor need we
be surprised at this departure from the general rule, where such an
anomalous inclination exists. In singular confirmation of this is Mr.
Lassell's observation of 1862, Jan. 29, where he says: "I received an
impression which I am unable to render certain of an equatorial dark
belt, and of an ellipticity of form."
Some observations made in 1872-3 with the great six-foot reflector of
Lord Rosse may here be briefly referred to. A number of measures, both
of position and distance, of Oberon and Titania, were made, [1] and a
few of Umbriel and Ariel, but "the shortness of the time available (40
minutes) each night for the observation of the planet with the six-foot
instrument, the atmospheric disturbance, so often a source of annoyance
in using so large an aperture, and other unfavorable circumstances,
tended to affect the value of the observations, and to make the two
inner satellites rarely within detection."
[Footnote 1: "Monthly Notices R. A. S.," March, 1875.]
On Feb. 10, 1872, Lord Rosse notes that all four satellites were seen on
the same side of the planet. On Jan. 16, 1873, when definition was good,
no traces of any markings were seen. Diameter of Uranus = 5.29". Power
414 was usually employed, though at times the inner satellites could be
more satisfactorily seen with 625.
It may be mentioned as an interesting point that, some fifty years
after the first discovery of Uranus by Herschel, it was accidentally
rediscovered by his son, Sir John Herschel, who recognized it by
its disk, and had no idea as to the identity of the object until an
ephemeris was referred to. Sir John mentions the fact as follows, in a
letter to Admiral Smyth, written in 1830, August 8:
Public-domain text, read in full here on John Shaqi.
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