FIXED STAKS CONSTELLATIONS. 



of the total number of stars, the existence of which the telescope 

 discloses to us. But we shall, for the present, limit our observa- 

 tions to the stars which are visible to the naked eye. 



It has been stated that the celestial objects generally maintain 

 with relation to each other a certain invariable position, and have 

 no other motion than that imparted to them in common by the 

 sphere to which they are imagined to be attached. To this, 

 however, there is a limited number of exceptions. There is a 

 small number of objects, among which the sun and moon are the 

 most conspicuous, which, while they participate in the diurnal 

 motion of the celestial sphere, are observed continually to shift 

 their position on it, just as if a number of insects were creeping 

 slowly upon the surface of a top while the top is spinning, carrying 

 the insects round with it. These objects, which, exclusive of the 

 sun and moon, are called Planets, have occupied our attention on 

 a former, and will again on a future, occasion ; for the present, 

 however, we must be understood to notice only those which main- 

 tain invariable relative positions, and which have therefore been 

 denominated Jixed stars. 



11. The nomenclature of the stars, so far as it is founded upon 

 their apparent relative positions, consists in the resolution of all 

 the stars of the firmament into a certain limited number of groups, 

 called Constellations. These groups have been from ancient 

 times invested with the imaginary forms of men, animals, and 

 various other objects, natural and artificial, and have been named 

 in accordance with these. Thus, the celestial spaces are par- 

 titioned out arbitrarily and conventionally into distinct compart- 

 ments, in a manner somewhat resembling the divisions of the land 

 on the surface of the globe into empires and kingdoms. Each 

 such compartment of the heavens contains a certain number of 

 stars, great and small, the total assemblage of which constitutes 

 the constellation, and is characterised by the proper name 

 conferred upon it. 



Since it is of the first necessity that the astronomical student 

 and amateur should be so familiar with this stellar nomenclature 

 as to be able readily to distinguish and recognise not only each 

 principal constellation, but also each principal star in such con- 

 stellation, we propose here to give such explanations as will 

 present the greatest practicable facilities in the attainment of this 

 object. 



The stars composing each constellation are designated by the 

 letters of the Greek alphabet, the first letters being given to the 

 more splendid stars. When the number of stars in a constellation 

 exceeds the number of letters in the Greek alphabet, the letters of 

 the Roman alphabet are used ; and when these are exhausted, the 



151 



