TS Scientific Intelligence. 



For two of the stars, Nos. 14 and 35, it seems to me the coin- 

 cidence is, considering the uncertainty of the absolute motion of 

 Alcyone, a quantity not easily to be estimated at present, quite 

 close enough to warrant the deduction that these two stars at least 

 do not belong to but form only optical members of the group. 

 For the other four it will be admitted that there is some possi- 

 bility, if not probability, that they also are only seen projected on 

 the group. 



" Of the remaining twenty-six of the thirty-two stars under con- 

 sideration, it will be found that the distribution of the direction 

 of motion is by no means equable, six stars only having an easter- 

 ly motion, while twenty move towards the west.* And although 

 it may prove to be fortuitous, and due to chance errors of obser- 

 vation, still it may be noted that there seems to be a tendency to 

 community of drift in certain groups in the same part of the clus- 

 ter, such as that formed by the stars 1, 2, 5, and 7, and that 

 shown by Nos. 3, 4, 6, 9, and 10. A third group seems to be 

 made up of the two sets 11, 12, 15, 20, and 31, 33, 37 ; and of the 

 six stars with an eastward drift five, Nos. 19, 25, s, 34, and 39, 

 are again about in the same direction. It is noteworthy that of 

 the ten brightest stars only two are to be counted among the ones 

 with some probability of displacement ; and for these two, b and 

 m, the divergences are very small, 0"*49 and 0" # 48 respectively, 

 confirming the conclusions reached by Professor Newcomb from 

 the discussion of the meridian observations that the relative 

 motions of the brighter stars are as yet in general insensible. For 

 star b, however, I think the motion in declination is unquestiona- 

 ble ; m, being only indirectly connected at Konigsberg with 

 Alcyone, is very much more uncertain. 



" The general character of the internal motions of the group 

 appears to be thus extremely minute. If for the six stars men- 

 tioned as with more or less probability not belonging to the group 

 this proves to be the case, there are but five stars for which the 

 displacement amounts to over l" in forty-five years. The bright 

 stars in especial seem to form an almost rigid system, as for only 

 one is there really much evidence of motion ; and in this case 

 (star b) the total amount is barely l" per century. The hopes of 

 obtaining any clew to the internal mechanism of this cluster seem 

 therefore not likely to be realized in an immediate future." 



The work upon this group by M. Wolf at Paris, and at the 

 University Observatory at Oxford is then compared with this at 

 Tale : " The outcome of these comparisons appears to show that 



* Lately, Professor Pickering, of Harvard, has photographed the spectra of the 

 Pleiades stars, and it is of some interest to note that the only two marked diver- 

 gences he has found among them are of two of the six stars having motions 

 opposite to those of the generality of the group, stars 5 and 39, in which the K 

 line is present. Star 25, which has a very similar motion to s, was unfortunately 

 not determined on the photograph, on account of its spectrum falling over some of 

 the others. Of the six stars which may very possibly prove not to belong to the 

 group, they are all but one too faint in the photograph to have the character of 

 the spectrum ascertained. The one, star 17, has the general spectrum of the 

 group. 



