PORTION OF THE COSMOS. NEBULA. 243 



nebula in Orion ( 426 ). Bouillaud and Le Gentil had as- 

 serted the same of the nebula in Andromeda. The con- 

 tinued investigations of the younger Herschel render these, 

 as it was supposed well assured, cosmical alterations, at least 

 exceedingly doubtful. 



Great nebula round ?; Argus. This nebula is situated 

 in that part of the Milky Way, so distinguished for its 

 brightness, which extends from the feet of the Centaur 

 through the Southern Cross to the middle portion of the 

 constellation of the Ship. The lustre of this region of the 

 heavens is so extraordinary that an accurate observer residing 

 in India, Captain Jacob, remarks, in full accordance with iny 

 own experience during four years passed within the tropics, 

 " that such is the general blaze from that part of the sky, 

 that a person is immediately made aware of its having risen 

 above the horizon, though he should not be at the time 

 looking at the heavens, by the increase of general illumination 

 of the atmosphere, resembling the effect of the young inoon" 

 (427) . Tn e nebula, in the middle of which the star ?/ Argus, 

 which has become so celebrated on account of the changes 

 of brightness which it has undergone ( 428 ), is situated, covers 

 above -f-ths of a square degree of celestial space. It consists 

 of several amorphous masses of unequal intensity of light, 

 and no where shows that mottled granular appearance whicli 

 is considered to indicate resolvability. It encloses a singu- 

 larly shaped vacuity covered with a very faint degree of 

 light, and forming a lengthened lemmiscate-oval. A fine 

 representation of the whole phenomenon, the fruit of two 

 months measurements, is found in the Cape Observations of 

 Sir John Herschel ( 42 9). This astronomer has determined 

 in the nebula of r? Argus not less than 1216 positions of stars 



