NOTES. 



this part of his subject without calling attention to the fact, that no real 

 nebula seemed to exist among so many of these objects, chosen without any 

 bias : all appeared to be clusters of stars, and every additional one which shall 

 be resolved will be an additional argument against the existence of any such" 

 (Schumacher, Astr. Nachr. No. 536). In the " Notice sur les grauds Tele- 

 scopes de Lord Oxmantown, aujourd'hui Earl of Rosse" (Bibliotheque univer- 

 selle de Geneve, T. lyii. 1845, p. 342357), it is said : " Sir James South 

 rappelle que jamais il n'a vu de representations siderales aussi magnifiques que 

 celles que lui offrait 1'instrument de Parsonstown ; qu'une bonne partie des 

 nebuleuses se presentaient comme des amas ou groupes d'etoiles, tandis que 

 quelques autres, a ses yeux du moins, n'offraient aucune apparence de resolu- 

 tion en etoiles." 



t 383 ) p. 226. Report of the Fifteenth Meeting of the British Association 

 held at Cambridge in June 1845, p. xxxvi. ; and Outlines of Astronomy, p. 

 597 and 598. " By far the major part," says Sir John Herschel, " probably 

 at least nine-tenths of the nebulous contents of the heavens, consist of nebulae 

 of spherical or elliptical forms, presenting every variety of elongatioa and 

 central condensation. Of these, a great number have been resolved into 

 distant stars (by the Reflector of the Earl of Rosse), and a vast number more 

 have been found to possess that mottled appearance which renders it almost 

 a matter of certainty that an increase of optical power would show them to 

 be similarly composed. A not unnatural or unfair induction would therefore 

 seem to be, that those which resist such resolution do so only in consequence 

 of the smallness and closeness of the stars of which they consist ; that in short 

 they are only optically and not physically nebulous. Although nebulee do 

 exist which even in this powerful telescope (of Lord Rosse) appear as nebulae 

 without any sign of resolution, it may very reasonably be doubted whether 

 there be really any essential physical distinction between nebulse and clusters 

 of stars." 



(3 s4 ) p. 226. Dr. Nichol, Professor of Astronomy at Glasgow, has published 

 in his " Thoughts on some Important Points relating to the System of the 

 World," 1846, p. 55, this letter, dated Castle, Parsonstown : " In accordance 

 with my promise of communicating to you the result of our examination of 

 Orion, I think I may safely say, that there can be little, if any, doubt as to 

 the resolvability of the nebula. Since you left us, there was not a single 

 night when, in the absence of the moon, the air was fine enough to admit of 

 our usiag more than half the magnifying power the speculum bears : still we 

 could plainly see that all about the trapezium is a mass of stars ; the rest of 



