324 COSMOS. 



and Apus, in the southern hemisphere.* 1 No two of the 



unsymmetrical, diffused nebulous masses resemble one an- 

 other; 17 but, adds Sir John Herschel, from the experience of 

 many years' observation, one thing observed in reference to 

 them, and which gives them a peculiar character, is, that 

 all are situated \vithin or very near to the margins of the 

 Milky Way, and may be regarded as off-shoots from it. On 

 the contrary, the regularly shaped and well-defined small 

 nebulous spots are partly scattered over the whole heavens, 

 and partly compressed together in special regions, far from 

 the Milky Way, as, for instance, in the northern hemisphere, 

 in the regions of Virgo and Pisces. Although the large 

 irregular nebulous mass in the sword of Orion is certainly 

 situated at a considerable distance from the visible margin 

 of the Galaxy (fully 15), still even it may perhaps belong 

 to that prolongation of its branch which appears to lose itself 

 from a and e Persei towards Aldebaran and the Hyadcs, and 

 to which we have already referred at p. 199. The brilliant 

 etars which gave early celebrity to the constellation of Orion, 



66 Observations at the Cape, p. 117, no. 3727, pi d. fig. 16. 



67 We meet with remarkable forms of irregular nebula), as, 

 for instance, the omega-shaped (Observations at the Cape, pi. ii. 

 fig. 1, No. 2008), which has been investigated and described 

 by Lamont, and by a meritorious North American astronomer, 

 Mr. Mason, whose early loss is much to be lamented (Mem. 

 of the Amer. Philos. Society, vol. vii. p. 117); a nebula having 

 from 6 to 8 nuclei (Observations at the Cape, p. 19, pi. iii. 

 fig. 4) ; the cometary tuft-like form in which the nebulous 

 rays seem occasionally to expand, as from a star of the ninth 

 magnitude (pi. vi. fig. 18, Nos. 2534 and 3688); a silhouette 

 profile, or bust-like outline (pi. iv. fig. 4. No. 3075); a 

 fissure-like opening, inclosing a filiform nebula. (No. 3501, 

 pi. iv. fig. 2 3 Outimes, 883; Observation* at the 



