2o 4 THE POPULAR SCIENCE MONTHLY. 



iants as Vega and Arcturus shows how wide is the range of magni- 

 tude among the suns that light the universe. The actual distance of 

 61 Cygni is something like 050,000 times as great as the distance from 

 the earth to the sun. 



The star Omicron (o) is very interesting with an opera-glass. The 

 naked eye sees a little star near it. The glass throws them wide 

 apart, and divides o itself into two stars. Now, a field-glass, if of 

 sufficient power, will divide the larger of these stars again into two 

 a fine test. 



Sweep around a and y for the splendid star-fields that abound in 

 this neighborhood ; also around the upper part of the figure of the 

 cross. We are here in one of the richest parts of the Milky-Way. 

 Between the stars a, y, e, is the strange dark gap in the galaxy called 

 the Coal-Sack, a sort of hole in the starry heavens. Although it is 

 not entirely empty of stars, its blackness is striking in contrast with 

 the brilliancy of the Milky- Way in this neighborhood. The divergent 

 streams of the great river of light in this region present a very remark- 

 able appearance. 



Finally, we come to the great dragon of the sky. In using the 

 map of Draco and the neighboring constellations, the reader is sup- 

 posed to face the north. The upper edge of the center of the map is 

 directly over the observer's head. One of the stories told of this large 

 constellation is that it represents a dragon that had the temerity to 

 war against Minerva. The goddess " seized it in her hand, and hurled 

 it, twisted as it was, into the heavens round the axis of the world, be- 

 fore it had time to unwind its contortions." Others say it is the dragon 

 that guarded the golden apples in the Garden of the Ilesperides, and 

 that was slain by the redoubtable Hercules. At any rate, it is plainly 

 a monster of the first magnitude. The stars /?, y, , v, and fx represent 

 its head, while its body runs trailing along, first sweeping in a long 

 curve toward Cepheus, and then bending around and passing between 

 the two bears. Try v with your opera-glass, and if you succeed in see- 

 ing it double you may congratulate yourself on your keen sight. The 

 distance between the stars is about 1'. Notice the contrasted colors 

 of y and (3, the former being a rich orange and the latter white. As 

 you sweep along the winding way that Draco follows, you will run 

 across many striking fields of stars, although the heavens are not as 

 rich here as in the splendid regions that we have just left. You will 

 also find that Cepheus, although not an attractive constellation to the 

 naked eye, is worth some attention with an opera-glass. It, however, 

 sinks into insignificance in comparison with its neighbor Cassiopeia, 

 but that constellation belongs rather to the autumn sky, and we shall 

 pass it by here. 



The reader will find it both interesting and instructive to w r atch 

 the movements of Venus through the summer. On June 1st as we 

 have seen, Venus will be near Saturn in the constellation Gemini. But 



