SCIENCE. 
9 
ASTRONOMY. 
Mr. Stone, F. R. S., the Radcliffe observer, has recently 
drawn the attention of astronomers to a most interesting 
system of stars in the Southern Hemisphere, which seems 
to present a remarkable case of an apparent connection be- 
tween stars widely distant from one another. 
Astronomers are familiar with cases of double stars, which 
seem connected together in some manner analogous to the 
Earth and Moon. But these stars are very close to one an- 
other.being only separated by a few seconds of arc. In the 
present case the stars form an isosceles triangle, with sides 
nearly 20 degrees in length and with a base of over 30 de- 
grees. This system of stars consists of two stars f 1 and f 2 
Reticitli , forming the apex of the triangle, and scarcely as 
bright as the fifth magnitude ; f Toucani , a fourth magni- 
tude star at the southern base angle, and e. Eridani , a star 
of between the fourth and fifth magnitude, at the northern 
base angle. All four stars are invisible from England. 
Besides the apparent motion in Right Ascension and 
the North Polar Distance, which is possessed by all 
stars, astronomers have long recognized the fact that 
many stars possess a real independent motion in space, 
which though much smaller than their apparent motion, 
is too large for its existence to remain in doubt. In gen- 
eral this proper motion, as it is called, amounts to only 
a small fraction of a second of arc per annum ; but in 
some few cases it amounts to considerably over a second of 
arc, or even to over two or three seconds of arc. 
In forming the Great Catalogue of Southern Stars, which 
has been the main work at the Royal Observatory at the 
Cape of Good Hope, whilst under his direction, Mr. Stone 
was led to examine all the cases of supposed great proper 
motion in the Southern Stars of the British Association 
Catalogue. In the greater number of cases they were found 
to arise from defective observations, but in some few cases 
they were confirmed. 
The most noteworthy instances were the group to which 
Mr. Stone has directed attention. From a careful con- 
sideration of each case, Mr. Stone arrived at the following 
conclusions : 
That the four stars of the group under consideration 
have proper motions much larger than the average proper 
motions of stars. 
That the stars have a common proper motion of more 
than a second of arc. 
That each star of the group is moving away from every 
other star of the group, by quantities which are small com- 
pared with the common proper motion of the group. 
That, roughly speaking, the velocities of separation are 
larger, the greater the present angular separation of the 
stars. ^ 
From these conclusions it seems probable that all these 
stars are slowly moving away from one common point, so 
that man}' years back they were all very much closer to one 
another, and may have formed part of one common star 
system. 
With the present rate of motion of separation it must 
have taken these stars over three million years to have 
moved to their present positions from a point where they 
would have been close together. 
Mr. Stone remarks that it appears to him that such a 
system of stars like a 1 and a 2 Centatiri, which consist of 
two binary stars moving round each other, and with a large 
common proper motion, having by reason of that large 
common proper motion been brought sufficiently near to 
another binary double star to disturb the orbital motion 
of each, and change the motion of each from closed to 
open orbits. The whole question opened by Mr. Stone is 
one of the highest interest, and deserves still further inves- 
tigation, when the proper time arrives. 
THE NEBULA IN THE PLEIADES. 
Some twenty years ago, Temple, whilst at Venice, dis- 
covered, with a four inch telescope, a fine bright nebula 
close to the bright star Merope in the Pleiades. It was ellip- 
tical in form, and covered an area of nearly a fifth of a 
square degree. Temple showed it to Valz and other astron- 
omers, and it was seen by Peters with the eight inch equa- 
orial of the Altona Observatory. 
Subsequently it was looked for by other observers, either 
without success, or else seen as a very faint, indistinct ob- 
ject. Even Temple, though it is true with another instru- 
ment and in another locality, describes it as being far less 
distinct than when first seen. Subsequently, when observ- 
ing near Florence with larger instruments, Temple saw the 
nebula as large and as bright as ever. Prof. Schiaperelli 
of Milan also observed it with the fine refractor at Milan, 
and describes it as bright and distinct, and completely sur- 
rounding the star Merope whilst outlaying portions seemed 
to extend as far as Electra. Schiaperelli remarks, it is 
singular that so many persons should have examined the 
Pleiades without paying attention to this great nebula, 
which, nevertheless, is so evident an object on a clear sky. 
Maxwell Hall, in Jamaica, also found the nebula very 
bright with a four inch telescope, and shows it as nearly 
half a square degree in area. Several astronomers came to 
the conclusion that the nebula was variable. Others even 
doubted its real existence, and were inclined to ascribe its 
supposed observation to the effects of atmospheric action. 
Of late it has been drawn by several observers, so that its 
real existence cannot be questioned. During this year it 
has been looked for by Mr. Common with the great 37-inch 
reflector at Ealing. The nebula was seen as a distinct ob- 
ject of considerable extent, but beyond it, and right within 
the Pleiades , were discovered two others, both long ellipti- 
cal nebulas of tolerable well defined form. There seems 
reason to believe, therefor, that the entire background of 
the Pleiades is nebulous. 
Dr. J. Lawrence Smith, of Louisville, Ky., has made a 
personal investigation of the great meteorite which fell in 
Emmett County in 1879, having visited the spot for the occa- 
sion. An interesting report may be seen in the American 
Journal of Science. The external appearance was that of a 
mass, rough and knotted like mulberry calculi, with rounded 
protuberances projecting from the surface. The larger por- 
tions were of a gray color, with a green mineral irregularly 
disseminated through it. The total weight of the portions 
found amounted to 307 pounds. The stoney part of this 
meteorite consisted essentially of bronzite and olivine, the 
three essential constituents being silica, ferrous oxides and 
magnesia. An analysis showed, that in composition the 
meteorite contained nothing that was peculiar. Its position, 
however, among meteorites is unique, on account of the 
phenomena accompanying its fall, especially the great depth 
to which it penetrated beneath the surface, and also because 
of its physical characters and the manner of association of 
its mineral constituents. 
I 
