344 HUMBOLDT'S COSMOS : 



ascertained, and to enlarge the conclusions derived from 

 them. 



While treating all these topics with his wonted ability 

 and care, we think that Humboldt somewhat too hastily 

 passes over the question of a common centre of gravity and 

 revolution of the sidereal system ; seeing those vast labours 

 of Madler in the Observatory of Dorpat, which, even if not 

 admitted to substantiate his opinion, do yet form one of the 

 eras in sidereal astronomy, and a basis for all future enquiry. 

 We cannot but admire the skillful approximations by which 

 he narrowed the field of research for this great centre : 

 limiting it first to the constellation Taurus ; and finally, by 

 testing the proper motions of each star in this region, 

 locating it in the group of the Pleiades and in the star 

 Alcyone, the centre of this group. Of the fourteen stars 

 which the telescope shows to be clustered round Alcyone, all 

 have their proper motions in the same direction and nearly 

 of the same amount ; and extending this remark to upwards 

 of one hundred stars within 4 5 of this centre, Madler found 

 that all which had any certain proper motion moved in such 

 exact conformity with his hypothesis, that he declared he 

 would abandon it if one star could be found within 25 of 

 the presumed centre, with a well-ascertained motion in an 

 opposite direction. If we durst allow anything of romance 

 to blend itself with pure astronomy, this theory, which places 

 amidst the Pleiades the centre of gravity of the universe of 

 stars composing our system, might well lay hold on the ima- 

 gination. It awakens the memory of the many passages of 

 poetry of every age by which this beautiful group has been 

 in some sort endeared to us. It recalls to mind the classic 

 story of the lost Pleiad. In the aspect, too, of these stars 

 there is much to engage the fancy. They are seen, in the 

 midst of an almost starless space, a close and brilliant cluster 

 inviting the eye to number them, yet by their compression 



