8 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ascension and north polar distance of every known double 

 star, it becomes a valuable aid to those who may be search- 

 ing for new ones, or to those who wish to add to our present 

 knowledge of these interesting subjects of observation. 

 Mem. of Hoy. Astr. Soc, XL. 



ORBIT OF A DOUBLE STAR. 



The double star, 70, Ophiuchi, which consists of a bright 

 yellow star of the 4^- magnitude, and a rose -colored star 

 of the sixth magnitude, was first observed by Sir William 

 Herschel in 1779, and has since formed a favorite subject of 

 observation for observers in both hemispheres. Some com- 

 putations based on these observations have lately been made 

 by Flammarion, in order to determine the apparent orbit 

 and, if possible, the true orbit of this sidereal system. Flam- 

 marion's results are practically identical with those of Klin- 

 kerfues, as deduced a number of years ago. Flammarion, 

 assuming the parallax as determined by Krtiger, concludes 

 the distance of these stars from the earth to be 1,400,000 

 times that of the sun, and the actual distance of the two stars 

 from each other to be somewhat less than the distance of 

 Neptune from the sun. The relative movement of the stars 

 is, according to Klein, 1.65 that of Neptune and the sun. 

 The two stars have, however, a common movement through 

 space, which is three and a half times as great as their orbit- 

 al velocities about each other. 19 (7, VIII., 46. 



THE ORBIT OF THE DOUBLE STAR " MU BOOTIS." 



Among the theses published by the University of Kasan, 

 in Russia, is an investigation into the orbit of the double star 

 Mu Bootis, by Venogradski. Observations of this star have 

 been made since 1782, when it was first observed by the 

 elder Herschel ; and its orbit has been investigated once pre- 

 viously by Wilson, but the computations of Venogradski 

 take precedence, inasmuch as he has had access to very ac- 

 curate and long-continued observations of Otto Struve and 

 Dembowski. Daring the past ninety years the smaller star 

 lias described nearly one half of its orbit about the larger 

 one ; and the mutual distance has diminished from one and 

 a half seconds to less than half a second. According to the 

 present computation, the periodic time of these stars is about 



