200 THE POPULAR SCIENCE MONTHLY. 



tricities. Sometimes it attains nearly the fourth magnitude, 

 although usually at maximum it is below the fifth, while at 

 minimum it is occasionally of the sixth and at other times of the 

 seventh or eighth magnitude. Its period is irregular. 



Turning back to Sagittarius, we resume our search for interest- 

 ing objects there, and the first that we discover is another star 

 cluster, for the stars are wonderfully gregarious in this quarter 

 of the heavens. The number our cluster bears on the map is 

 4424, corresponding with M 22 in Messier's catalogue. It is very 

 bright, containing many stars of the tenth and eleventh magni- 

 tudes, as well as a swarm of smaller ones. Sir John Herschel 

 regarded the larger stars in this cluster as possessing a reddish 

 tint. Possibly there was some peculiarity in his eye that gave 

 him this impression, for he has described a cluster in the constel- 

 lation Toucan in the southern hemisphere as containing a globu- 

 lar mass of rose-colored stars inclosed in a spherical shell of 

 white stars. Later observers have confirmed his description of 

 the shape and richness of this cluster in Toucan, but have been 

 unable to perceive the red hue of the interior stars. 



The eastern expanse of Sagittarius is a poor region compared 

 with the western end of the constellation, where the wide stream 

 of the Milky Way like a great river enriches its surroundings. 

 The variables T and R are of little interest to us, for they never 

 become bright enough to be seen without the aid of a telescope. 

 In 54 we find, however, an interesting double, which with larger 

 telescopes than any of ours appears as a triple. The two stars 

 that we see are of magnitudes six and seven and a half ; distance 

 45", p. 42, colors yellow and blue. The third star, perhaps of 

 thirteenth magnitude, is distant 36", p. 245. 



Retaining map No. 13 as our guide, we examine the western 

 part of the constellation Capricornus. Its leader a is a naked-eye 

 double, the two stars being a little more than 6' apart. Their 

 magnitudes are three and four, and both have a yellowish hue. 

 The western star is a 1 , and is the fainter of the two. The other is 

 designated as a 2 . Both are double. The components of a 1 are 

 of magnitudes four and eight and a half ; distance 44", p. 220. 

 With the Washington twenty-six-inch telescope a third star of 

 magnitude fourteen has been found at a distance of 40", p. 182. 

 In a the magnitudes of the components are three and ten and a 

 half; distance 7'4", p. 150. The smaller star has a companion of 

 the twelfth or thirteenth magnitude ; distance 1'2", p. 240. This, 

 of course, is hopelessly beyond our reach. Yet another star of 

 magnitude nine, distance 154", p. 150, we may see easily. 



Dropping down to /3, we find it to be a most beautiful and 

 easy double, possessing finely contrasted colors, gold and blue. 

 The larger star is of magnitude three, and the smaller, the 



