ASTRONOMY WITH AN OPERA-GLASS. 515 



eastward, and finally flowing back more than half-way to Orion, and 

 then curving south again and disappearing beneath the horizon. 

 Throughout this whole distance of more than 100° the course of the 

 stream is marked by rows of stars, and can be recognized without 

 difficulty by the amateur observer. 



The first thing to do with your opera-glass, after you have fixed the 

 general outlines of the constellation in your mind by naked eye obser- 

 vations, is to sweep slovv^ly over the whole course of the stream, begin- 

 ning at Rigel, and following its various wanderings. Eridanus ends in 

 the southern hemisphere near a first-magnitude star called Achernar, 

 which is situated in the stream, but can not be seen from our latitudes. 

 Along the stream you will find many interesting groupings of the 

 stars. In the map see the pair of stars below and to the right of Nu 

 iy). These are the two Omicrons, the upper one being o' and the 

 lower one o^ The latter is of an orange hue, and is remarkable for 

 the speed with which it is fiying through space. There are only one 

 or two stars whose proper motion, as it is called, is more rapid than that 

 of o'' in Eridanus. It changes its place nearly seven minutes of arc in 

 a century. The records of the earliest observations we possess show 

 that near the beginning of the Christian era it was about half-way 

 between o' and v. Its companion, o', on the contrary, seems to be al- 

 niost stationary, so that o" will gradually draw away from it, passing 

 on toward the southwest until, in the course of centuries, it will be- 

 come invisible from our latitudes. This flying star is accompanied by 

 two minute companions, which in themselves form a close and very 

 delicate double star. These two little stars, of only 9"5 and 10*5 mag- 

 nitude, respectively, are, of course, beyond the ken of the observer 

 with an opera-glass. The system of which they form a part, however, 

 is intensely interesting, since the appearances indicate that they be- 

 long, in the manner of satellites, to o^, and are fellow-voyagers of that 

 wonderful star. 



Having admired the star-groups of Eridanus, one of the prettiest 

 of which is to be seen around Beta (/?), let us turn next to Taurus, just 

 above or north of Eridanus. Two remarkable clusters at once attract 

 the eye, the Hyades, which are shaped somewhat like the letter V, 

 with Aldebaran in the upper end of the left-hand branch, and the 

 Pleiades, whose silvery glittering has made them celebrated in all 

 ages. The Pleiades are in the shoulder and the Hyades in the face of 

 Taurus, Aldebaran most appropriately representing one of his blazing 

 eyes as he hurls himself against Orion. The constellation makers did 

 not trouble themselves to make a complete Bull, and only the head 

 and fore-quarters of the animal are represented. If Taurus had been 

 completed on the scale on which he was begun there would have been 

 no room in the sky for Aries ; one of the Fishes would have had to 

 abandon his celestial swimming-place, and even the fair Andromeda 

 would have found herself uncomfortably situated. But as if to make 



