ASTEO.YOMY WITH jLV OPERA-GLASS. 59 



which a <|uai'ter of a century later made the name of Sir William 

 Herschel world-renowned. The planet Uranus passed near Delta in 

 1756, and Tobias Mayer saw it, but it moved so slowly that he took it 

 for a fixed star, never suspecting that his eyes had rested upon a mem- 

 ber of the solar system w^hose existence was, up to that time, unknown 

 to the inhabitants of Adam's planet. 



Above Aquarius you will find the constellation Pegasus. It is con- 

 spicuously marked by four stars of about the second magnitude, which 

 shine at the corners of a large square, called the Great Square of Pega- 

 sus. This figure is some fifteen degrees square, and at once attracts 

 the eye, there being few stars visible within the quadrilateral, and no 

 large ones in the immediate neighborhood to distract attention from 

 it. One of the four stars, however, as will be seen by consulting Map 

 2, does not belong to Pegasus, but to the constellation Andromeda. 

 Mythologically, this constellation represents the celebrated winged 

 horse of antiquity : 



" Now heaven his further wandering flight confines, 

 Where, splendid with his numerous stars, he shines." 



The star Alpha (a) is called Markab ; Beta (/3) is Scheat, and 

 Gamma (y) is Algenib ; the fourth star in the square, belonging to 

 Andromeda, is called Alpheratz. Although Pegasus presents a strik- 

 ing appearance to the unassisted eye, on account of its great square, 

 it contains little to attract the observer with an opera-glass. It will 

 prove interesting, however, to sweep with the glass carefully over the 

 space within the square, which is comparatively barren to the naked 

 eye, but in which many small stars will be revealed, of whose exist- 

 ence the naked-eye observer would be unaware. The star marked Pi 

 (tt) is an interesting double, which can be separated by a good eye 

 without artificial aid, and which, with an opera-glass, presents a fine 

 appearance. 



And now we come to our third little map, representing the constel- 

 lations Cetus, Pisces, Aries, and the Triangles. In consulting it the 

 observer is supposed to face the southeast. Cetus is a very large con- 

 stellation, and from the peculiar conformation of its principal stars it 

 can be I'eadily recognized. The head is to the east, the star Alpha 

 (a), called Menkai", being in the nose of this imaginary monster of the 

 sky-depths. This constellation is supposed to represent the monster 

 that was sent, according to the fable, by Neptune to devour the fair 

 Andromeda, but whose bloodthirsty design was happily and gallantly 

 frustrated by Perseus, as we shall learn from starry mythology far- 

 ther on. 



By far the most interesting object in Cetus is the star Mira, marked 

 Oraicron (o) in the map. This is a famous variable star — a sun that 

 sometimes shines a thousand times more brilliantly than at others ! 

 It changes from the second magnitude to the ninth or tenth, its period 



