THE STELLAR UNIVERSE. 



The elements Nos. 1, 2, 3, 4 c, 5, 6 c, 7, 11 b, 12 a, are extracted 

 from M. Miidler's synoptic view of the history of double stars, in vol. ix. 

 of the Dorpat Observations : 4 a, from the Connoiss. des Temps, 1830 : 

 4 b, 6 b, and 11 a, from vol. v. Trans. Astron. Soc. Lond. : 6 a, from 

 Berlin Ephemeris, 1832 : No. 8. from Trans. Astron. Soc. vol. vi. : 

 No. 9, 11 c, 12 b, and 13 from Notices of the Astronomical Society, 

 vol. vii. p. 22., and viii. p. 159., and No. 10 from Sir John Herschel's 

 " Results of Astronomical Observations, &c., at the Cape of Good Hope," 

 p. 297. The 2 prefixed to No. 7 denotes the number of the star in 

 M. Struve's Dorpat Catalogue (Catalogus Novus Stellarum Duplicium, &c., 

 Dorpat. 1827), which contains the places for 1826 of 3112 of these 

 objects. 



The "position of the node" in col. 4, expresses the angle of position of 

 the line of intersection of the plane of the orbit, with the plane of the 

 heavens on which it is seen projected. The "inclination" in col. 6, is 

 the inclination of these two planes to one another. Col. 5, shows the angle 

 actually included in the plane of the orbit, between the line of nodes 

 (defined as above) and the line of apsides. The elements assigned in this 

 table to <a Leonis, Bootis, and Castor must be considered as very doubtful, 

 and the same may perhaps be said of those ascribed to n 2 Bootis, which 

 rest on too small an arc of the orbit, and that too imperfectly observed, to 

 afford a secure basis of calculation. 



62. The most remarkable of these, according to Sir John 

 Herschel, is y Virginis ; not only on account of the length of its 

 period, but by reason also of the great diminution of apparent 

 distance and rapid increase of angular motion about each other, of 

 the individuals composing it. It is a bright star of the fourth 

 magnitude, and its component stars are almost exactly equal. 

 It has been known to consist of two stars since the beginning of 

 the eighteenth century, their distance being then between six and 

 seven seconds ; so that any tolerably good telescope would resolve 

 it. Since that time they have been constantly approaching, and 

 are at present hardly more than a single second asunder ; so that 

 no telescope that is not of very superior quality, is competent to 

 show them otherwise than as a single star somewhat lengthened in 

 one direction. It fortunately happens that Bradley, in 1718, 

 noticed and recorded, in the margin of one of his observation- 

 books, the apparent direction of their line of junction as being 

 parallel to that of two remarkable stars a and 8 of the same con- 

 stellation, as seen by the naked eye. They are entered also as 

 distinct stars in Mayer's catalogue ; and this affords also another 

 means of recovering their relative situation at the date of his 

 observations, which were made about the year 1756. Without 

 particularising individual measurements, which will be found in 

 their proper repositories, it will suffice to remark, that their whole 

 series is represented by an ellipse. 



63. To understand the curious effects which must attend the 

 case of a lesser sun with its attendant planets revolving round a 



4 



