146 Transactions. — Miscellaneous. 



to see, as Argo Navis, Crux Australis, the Milky Way between 

 Scorpio and Centaurus, with the two neighbouring first-class 

 stars in the legs of the Centaur, commonly called the 

 " Pointers." Moreover, in the same region, and among them, 

 are some curious and peculiarly-attractive objects, very plainly 

 visible on clear nights. I will just refer to some of them : — 



(1.) Those two dark adjacent spaces, called by the old 

 navigators " Coal-sacks," near Centaurus and the Southern 

 Cross ; these black and apparently starless vacancies are, 

 however, occupied by many telescopic stars. 



(2.) Two others, distinct white patches, known by the 

 name of the "Magellanic Clouds," are not far off from the 

 Coal-sacks, the upper being termed the "Nubecula Major," 

 and the lower the " Nubecula Minor." 



(3.) The constellation Crux Australis, or the Southern 

 Cross, always visible, and forming with the two " Pointers " 

 such a glorious sight on a starlight night, has ever been an 

 object of universal attraction. The upper and lower stars, 

 being of similar right ascension, are always on the meridian 

 about the same time, and consequently serve to indicate the 

 approximate position of the South Pole, which is distant 

 about 27" 38' from the largest and nearest star in the Cross. 

 Here with us this constellation never sets below the horizon. 

 It also presents to our view the daily movements of a south 

 circumpolar star, so beautifully shown by the group of four 

 stars composing it. In the course of the day the constellation 

 will have made a complete circuit round the South Pole. In 

 this week (of May) those four principal stars are on the upper 

 meridian at 8.45 p.m. ; on the next day, at 2.44 a.m., the 

 earth will have turned on its axis through one-quarter of its 

 revolution ; the stars will therefore apparently have passed 

 over one quadrant, or the fourth part of the circuit, being at 

 that time due west of the South Pole. At 8.43 a.m. they 

 have performed one-half of their circuit, being now near the 

 horizon on the lower meridian. At 2.42 p.m. they are due 

 east of the South Pole, while the complete revolution is made 

 at 8.41 p.m. At the hour of midnight this constellation is in 

 the four positions — north, west, south, and east of the South 

 Pole — at the end of March, June, September, and December 

 respectively. The two principal stars in Centaurus (already 

 mentioned) are both easily recognised above Crux Australis ; 

 Alpha Centauri, the celebrated double star, being that nearer 

 the meridian, while Beta Centauri is between it and Beta 

 Crucis, the most easterly of the four principal stars in the 

 Cross. Alpha Centauri is one of the largest double stars in 

 the heavens, and one of the nearest to our solar system. This 

 double star has been frequently observed for the determination 

 of its parallax. 



