SCIENCE. 



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 C and £ 2 

 Reticuli, 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 appaient 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 many 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> and a 1 Centauri, 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 a a area of nearly a fifth 6f 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. 



