334 IIUMBOLDT'S COSMOS: 



been known to us which it may now take centuries to 

 disclose. 



After describing the distribution of the stars and the Milky 

 Way, the great trunk of our sidereal system, M. Humboldt 

 proceeds to treat of the newly appearing and vanishing 

 stars ; and of those which exhibit variations, periodical or 

 otherwise, in brilliancy or colour of light. This again is a 

 part of astronomy fertile for both reason and imagination to 

 work in. It records great mutations in the remote worlds of 

 the universe the causes known to us by hypothesis only.* 

 The new star seen in the time of Hipparchus led him to 

 begin his catalogue, and suggested to Pliny the question 

 StellcB an obirent, nascerenturve? an enquiry still un- 

 resolved, and which probably may ever remain so. Ap- 

 pearance or disappearance do not needfully imply creation 

 or extinction. Light is the sole medium through which we 

 have intimation of these events ; and we know, by the 

 instances of the planets of our own system, that the celestial 

 masses are not necessarily self-luminous, and may be rendered 

 so by reflection only. But the suddenness of the event in 

 certain of these cases shows undoubtedly some mighty acts 

 of change, which we can contemplate only in their results. 

 The fact long noted, that a large proportion, if not all, of the 

 new stars observed have appeared in or near the Milky Way, 

 has done more to excite than aid conjecture; and we must 

 not stop to relate the speculations which have been hazarded 

 on the subject, as none of them have any higher sanction than 

 that of possibility. They are however in some degree justified 

 by the limited number of contingencies open to us, and 



* That excellent observer, Mr. Cooper, working in his private Observatory 

 near Sligo, and preparing a catalogue of 60,000 stars near the ecliptic, found that 

 77 stars, peculiarly noted, had disappeared, nearly 50 of which had come under 

 his own prior observation. The planetoids between Mars and Jupiter will 

 probably account for some of these disappearances, but certainly not for all. 



