COSMOS. 



VII. 



NEBULOUS SPOTS. ARE THESE ONLY REMOTE AND VERY 



DENSE CLUSTERS OF STARS ? THE TWO MAGELLANIC 



CLOUDS, IN WHICH CROWDED NEBULOUS SPOTS ARE IN- 

 TERSPERSED WITH NUMEROUS STELLAR SWARMS. THE SO- 

 CALLED COAL-SACKS OP THE SOUTHERN HEMISPHERE. 



AMONG the visible cosmical bodies occupying the regions 

 of space, besides those which shine with stellar light (wheth- 

 er self-luminous, or illumined like planets, stars isolated or 

 in multiple groups, and revolving round a common center of 

 gravity), there are also masses which present a faint and 

 milder nebulous light* These bodies, which appear at one 

 time as sharply defined, disk-formed, luminous clouds, at 

 another as irregularly and variously-shaped masses, widely 

 diffused over large spaces, seem to the naked eye, at first 

 sight, to be wholly different from those cosmioal bodies of 

 which we treated fully in the last four sections of the Astrog- 

 nosy. In the same way that there is an inclination to infer 

 from the observed and as yet unexplained motion of the vis- 

 ible cosmical bodies,! the existence of others hitherto invisi- 

 ble, so the knowledge gained as to the resolvability of a con- 

 siderable number of nebulous spots has recently led to con- 

 clusions regarding the non-existence of all nebulsB, and, in- 

 deed, of all cosmical vapor generally. But whether these 

 well-defined nebulous spots be a self-luminous vapory mat- 

 ter, or remote, closely-thronged globular clusters of stars, they 

 must ever remain objects of vast importance in the knowl- 

 edge of the structure of the universe and of the contents of 

 space. 



The number whose positions have been determined by 

 right ascension and decimation exceeds 3600. Some of the 



* Cosmos, vol. i., p. 85-89, 91, and 142; vol. ii., p. 328; vol. iii., p 

 37-41, 140, 154, and 162. t Cosmos, vol. iii., p. 185, 186 



