230 ANNUAL OF SCIEXTTFIC DISCOVERT. 



The clustering " stars" of which, according to Lord Rossc and 

 Professor W. C. Bond, the brighter portions of this nebula con- 

 sist, cannot be supposed to be invisible in the spectrum ap[)aratus 

 because of their faintness, an opinion which is probal)ly correct of 

 the minute and widely separated "stars" seen in the Dumb-bell 

 Nel)ula. Tlic I'vidcnce afl'orded l)ythe largest tislescopes ai)p('ars 

 to be, that the brighter parts of the neljula in Orion consist of a 

 " mass of stars; " the whole, or the greater part of tlie light from 

 this ])art of tin; nebula, puist tlicrefore be regarded as tlie unittid 

 radiation of these numerous stellar points. 2s'ow it is this ligiit 

 which, when analyzed by the prism, reveals to us its gaseous 

 source ; and the bright lines indicative of gaseous constitution 

 are free iVom any tract; of a continuous spectrum, such as that 

 exhiliited by all tlu' l)righter stars hitherto examined. 



The conclusion is obvious, that the detection in a nebula, of 

 minute, closely associated, points of light, which oI;servation has 

 hitherto been considered as a certain indication of a sUdlar consti- 

 tution, can no longer bo accepteil as a trustworlliy proof that tlie 

 object consists of true stars. These luminous jjoints, in s(niie 

 nebnhe, at least, must be regardeil as themselv-es gaseous bodies, 

 dens(>r portions, j)robal»ly, of the gn;at nebulous mass, since they 

 exhibit a constitution M'hich is identical witii the fainter and out- 

 lying parts which have not been resolved. These nebulae are 

 shown l)y the prism to be enormous gaseous systems ; and the 

 conjecture appears probable that their ai)parent permanence of 

 general form is maintained by tiie continual motions of these 

 denser portions, wliich the telescoi)e reveals as lucid points. 



Mr. Iluggins, in his very suggestive paper, does not stop hei'e ; 

 he points out tliat the projjcr motion of this nebula has not yet 

 been infjuired into, because ever^ljod}', looking upon them as irre- 

 solvable clusters, thought them intinitely remote. Now, however, 

 that we know that they are not clusters of " stai's," properly so 

 called, it is possible that they may I)e much nearer to us than Ave 

 imagine. Tlie strange variability of the fifth and sixth stars in 

 the trapezium should not here be passed over in silence, while we 

 remark that Bond's latest observations tend to show that the proper 

 motion of the nebula cannot be different from that of the stars in 

 the trapezium. 



At all events, it is to be hoped that the present fiivorable position 

 of Orion will secure for the glori<nis nebula a searching scrutiny 

 with the largest instruments. This can scarcely fail to supply us 

 with new facts. In the meantime, what of the various shapes as- 

 sumed by the gaseous nebuke, from the brilliant and most irregu- 

 lar one of Orion to the faintest and most perfectly rounded plane- 

 tary one ? Must we look upon them as other evidences of celestial 

 dynamics? 



M. Otto Struve, the eminent director of the Pulkowa Observa- 

 tory, and Father Secchi, have recently been examining the nebula 

 with the magnificent nine-inch Merz of the Roman College. The 

 fact of changes having taken place is put beyond doubt by their 

 observations. — Header. 



