478 THE POPULAR SCIENCE MONTHLY. 



beautiful coutrast. We should make a sad mistake if we regarded 

 this wonderful distribution of color among the double stars as 

 accidental. It is manifestly expressive of their physical condition, 

 although we can not yet decipher its exact meaning. 



The binary 43 Comse Berenicis is too close for ordinary tele- 

 scopes, but it is highly interesting as an intermediate between 

 those pairs which the telescope is able to separate and those like 

 /? Aurigfe which no magnifying power can divide, but which 

 reveal the fact that they are double by the periodical splitting of 

 their spectral lines. The orbit in 42 Comse Berenicis is a very 

 small one, so that even when the components are at their greatest 

 distance apart they can not be separated by a five or six inch 

 glass. Burnham, using the Lick telescope, in 1890 made the dis- 

 tance 07"; Hall, using the Washington telescope, in 1891 made 

 it a trifle more than 0"5". He had measured it in 1880 as only 0*27". 

 The period of revolution is believed to be about twenty-five years. 



In Coma Berenices there is an outlying field of the wonderful 

 nebulous region of Virgo, which we may explore on some future 

 evening. But the nebulae in Coma are very faint, and, for an 

 amateur, hardly worth the trouble required to pick them up. The 

 two clusters included in the map, 2752 and 3453, are bright enough 

 to repay inspection with our largest aperture. 



Although Hydra is the largest constellation in the heavens, 

 extending about seven hours, or 105, in right ascension, it con- 

 tains comparatively few objects of interest, and most of these are 

 in the head or western end of the constellation, which we exam- 

 ined during our first night at the telescope. In the central portion 

 of Hydra, represented on map No. 7, we find its leading star a, 

 sometimes called Alphard, or Cor Hydra>, a bright second-magni- 

 tude star that has been suspected of variability. It has a decided 

 orange tint, and is accompanied, at a distance of 281", p. 153, by 

 a greenish tenth-magnitude star. Bu. 339 is a fine double, mag- 

 nitudes eight and nine and a half, distance 1*3", p. 216. The 

 planetary nebula 2102 is about 1' in diameter, pale blue in color, 

 and worth looking at, because it is brighter than most objects of 

 its class. Tempel and Secchi have given wonderful descriptions 

 of it, both finding multitudes of stars intermingled with nebulous 

 matter. 



For a last glimpse at celestial splendors for the night, let us 

 turn to the rich cluster 1630, in Argo, just above the place where 

 the stream of the Milky Way here bright in mid-channel and 

 shallowing toward the shores separates into two or three cur- 

 rents before disappearing behind the horizon. It is by no means 

 as brilliant as some of the star clusters we have seen, but it gains 

 in beauty and impressiveness from the presence of one bright 

 star that seems to captain a host of inferior luminaries. 



