318 Chronicles of Science. [April, 



Lord Eosse and Professor Bond, the brighter portions of this nebula 

 consist, cannot be supposed to be invisible in the spectuum apparatus 

 because of their faintness — an opinion which is probably correct of 

 the minute and widely-separated stars seen in the Dumb-bell nebula. 

 The evidence afforded by the largest telescopes appears to be, that the 

 brighter parts of the nebula in Orion consist of a " mass of stars ;" 

 the whole, or the greater part of the light from this part of the nebula, 

 must therefore be regarded as the united radiation of these numerous 

 stellar points. Now it is this light which, when analyzed by the 

 prism, reveals to us its gaseous source, and the bright lines indicative 

 of gaseity are free from any trace of a continuous spectrum, such as 

 that exhibited by all the brighter stars which have been examined. 



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

 closely associated points of light, which has hitherto been considered 

 as a certain indication of stellar constitution, can no longer be accepted 

 as a trustworthy proof that the object consists of true stars. These 

 luminous points, in some nebulas at least, must be regarded as them- 

 selves gaseous bodies, denser portions probably of the great nebulous 

 mass, since they exhibit a constitution which is identical with the 

 fainter and outlying parts which have not been resolved. These 

 nebulas are shown by the prism to be enormous gaseous systems ; and 

 the conjecture appears probable that their apparent permanence of 

 general form is maintained by the continual motions of these denser 

 portions which the telescope reveals as lucid points. 



The opinions which have been entertained of the enormous dis- 

 tances of the nebulas, since these have been founded upon the sup- 

 posed extent of remoteness at which stars of considerable brightness 

 would cease to be separately visible in our telescope, must now be 

 given up, in reference at least to those of the nebulas the matter of 

 which has been established to be gaseous. 



It is much to be desired that proper motion should be sought for 

 in those of the nebulas which are suitable for this purpose ; indi- 

 cations of parallax might possibly be detected in some, if any 

 nebulas could be found that would admit of this observation. If this 

 view of the greater nearness to us of the gaseous nebulas be accepted, 

 the magnitudes of the separate luminous masses which the telescope 

 reveals as minute points, and the actual intervals existing between 

 them, would be far less enormous than we should have to suppose 

 them to be on the ordinary hypothesis. It is worthy of consideration, 

 that all the nebulas which present a gaseous spectrum exhibit the same 

 three bright lines ; in one case only, 18 H. IV., was a fourth line seen. 

 If we suppose the gaseous substance of these objects to represent the 

 " nebulous fluid" out of which, according to the hypotbesis of Sir W. 

 Herschel, stars are to be elaborated by subsidence and condensation, 

 we should expect a gaseous spectrum in which the groups of bright 

 lines were as numerous as the dark lines due to absorption which are 

 found in the spectra of the stars. Moreover, if the improbable sup- 

 position be entertained, that the three bright lines indicate matter in 

 its most elementary forms, still we should expect to find in some of 

 the nebulas, or in some parts of them, a more advanced state towards 



