192 THE POPULAR SCIENCE MONTHLY. 



The object above and to the left of Antares, marked in the map 80 

 M., is a nebula, and although the nebula itself is too small to be seen 

 with an opera-glass (a field-glass shows it as a mere wisp of light), yet 

 there is a pretty array of small stars in its neighborhood worth look- 

 ing at. Besides, this nebula is of special interest, because in 1860 a 

 star suddenly took its place. At least, that is what seemed to have 

 happened. What really did occur, probably, was that a variable or 

 temporary star, situated between us and the nebula, and ordinarily 

 too faint to be perceived, received a sudden and enormous accession 

 of light, and blazed up so brightly as to blot out of sight the faint 

 nebula behind it. If this star should make its appearance again, it 

 could easily be seen with an opera-glass, and so it will not be useless 

 for the reader to know where to look for it. The quarter of the 

 heavens with which we are now dealing is famous for these celestial 

 conflagrations, if so they may be called. 



We shall presently see some examples of star-clusters and nebulas 

 with which the instruments we are using are better capable of deal- 

 ing. In the mean time, let us follow the bending row of stars from 

 Antares toward the south and east. When you reach the star Mu (/a), 

 you are not unlikely to stop with an exclamation of admiration, for 

 the glass will separate it into two stars that, shining side by side, 

 seem trying to rival each other in brightness. But the next star 

 below fx, marked Zeta (), is even more beautiful. It also separates 

 into two stars, one being reddish and the other bluish in color. The 

 contrast in a clear night is very pleasing. But this is not all. Above 

 the two stars you will notice a curious nebulous speck. Now, if you 

 have a powerful field-glass, here is an opportunity to view one of the 

 prettiest sights in the heavens. The field-glass not only makes the 

 two stars appear brighter, and their colors more pronounced, but it 

 shows a third, fainter star below them, making a small triangle, and 

 brings other still fainter stars into sight, while the nebulous speck 

 above turns into a charmingly beautiful little star-cluster, whose com- 

 ponents are so close that their rays are inextricably 

 mingled in a maze of light. This little cut is an 

 attempt to represent the scene, but no engraving 

 can reproduce the life and sparkle of it. 



Following the bend of the Scorpion's tail up- 

 ward, we come to the pair of stars in the sting. 

 These, of course, are thrown wide apart by the 

 opera -glass. Then let us sweep off to the east- 



ZETA SCORPIONIS. -ii-i T^-iii 



ward a little way and find the cluster known as 

 7M. You will see it marked on the map. Above it, and near enough 

 to be included in the same field of view, is 6 M., a smaller cluster. 

 Both of these have a sparkling appearance with an opera-glass, and 

 by close attention some of the separate stars in 7 M. may be de- 

 tected. With a field-glass these clusters become much more strik- 



