TEMPORARY STARS. 209 



of the theories of transition of the cosmical vapour into clus- 

 ters of stars, of an agglomerative force, of a concentration 

 to a central nucleus, and of hypotheses of a gradual formation 

 of solid bodies out of a vaporous fluid; views which were 

 generally received in the beginning of the nineteenth cen- 

 tury, but which at present, owing to the ever-changing 

 fluctuations in the world of thought, are in many respects 

 exposed to new doubts. 



Among newly-appeared temporary stars the following 

 (though with variable degrees of certainty) may be reckoned. 

 I have arranged them according to the order in which they 

 respectively appeared. 



Milky Way, builds much on the remarkable passages of Aris- 

 totle on the connexion of the tails of comets (the vapoury 

 radiation from their nuclei with the galaxy to which I have 

 already alluded. (Cosmos, vol. i. p. 88.) 



VOL. III. P 



