42 Prof. Phillips on the Planet Mars. [Jan. 26, 



nebulae, since these have been founded upon the supposed extent of remote- 

 ness 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 nebulae 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 nebulae which are suitable for this purpose ; indications of 

 parallax might possibly be detected in some, if any nebulae could be found 

 that would admit of this observation. 



If this view of the greater nearness to us of the gaseous nebulae be ac- 

 cepted, 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 nebulae 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 

 hypothesis of Sir Wm. 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 absorp- 

 tion which are found in the spectra of the stars. Moreover, if the im- 

 probable supposition be entertained, that the three bright lines indicate 

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

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

 the formation of a number of separate bodies, such as exist in our sun 

 and in the stars ; and such an advance in the process of formation into stars 

 would have been indicated by a more complex spectrum. 



My observations, as far as they extend at present, seem to be in favour 

 of the opinion that the nebulae which give a gaseous spectrum, are systems 

 possessing a structure, and a purpose in relation to the universe, altogether 

 distinct and of another order from the great group of cosmical bodies to 

 which our sun and the fixed stars belong. 



The nebulous star i Orionis was examined, but no peculiarity could be 

 detected in its continuous spectrum*. 



III. " Further Observations on the Planet Mars." By JOHN PHILLIPS, 

 M.A., LL.D., F.R.S., F.G.S., Professor of Geology in the Uni- 

 versity of Oxford. Received January 12, 1865. 

 The return of Mars to his periodical opposition with the sun has enabled 

 me to offer a few observations on this planet, in addition to those which 

 on a former occasion I had the honour to present to the Society)-. Among 



* Admiral Smyth appears to have always maintained that the results of telescopic 

 observation on the nebulas were insufficient to support the opinion that all these objects 

 were probably of stellar constitution. See his ' Cycle of Celestial Objects,' vol. i. p. 31G ; 

 and his ' Speculum Hartwellianum,' pp. 111114. 



t Proceedings of the Royal Society, 1863. 



