1872.] 



some Stars towards or from the Earth. 



393 



y, s, '( have also a common motion of recession, while the star a is ap- 

 proaching the earth. The star rj, indeed, appears to be moving from us, but 

 it is too far from a to be regarded as a companion to that star. 



Although it was not to be expected that a concurrence would always be 

 found between the proper motions which indicate the apparent motions at 

 right angles to the line of sight and- the radial motions as discovered by the 

 spectroscope, still it is interesting to remark that in the case of the stars 

 Castor and Pollux, one of which is approaching and the other receding, 

 their proper motions also are different in direction and in amount ; and 

 further, that y Leonis, which has an opposite radial motion to a and /3 of 

 the same constellation, differs from these stars in the direction of its 

 proper motion. 



It scarcely needs remark that the difference in breadth of the line H /3 in 

 different stars affords us information of the difference of density of the gas 

 by which the lines of absorption are produced. A discussion of the ob- 

 servations in reference to this point, and other considerations on the 

 physical condition of the stars and nebulae, I prefer to reserve for the 

 present. 



Table I. — Stars moving from Sun. 



Star. 



Sirius 



Betelgeux 



Rigel 



Castor 



Kegulus 



/3 TJrsaa majcris 



1 



% . 



/3 Leonis 



d Leonis 



t] Ursae majoris 



« Virginia 



a. Coronas boreali 



Procyon 



Capella 



Aldebaran ? 



y Cassiopeia} 



Compared 

 with 



H 

 Na 

 H 

 H 

 H 



H| 



H 



H 



H 



H 



H 



H 



H 



H 



H 



H 



Mg 



11 



Apparent 

 motion. 



26 to 36 



37 



30 



40 to 45 

 30 to 35 



30 



Earth's 

 motion. 



-10 to 14 



-15 



-15 



-17 



-18 



9 to 13 



Motion 

 from sun. 



18 to 22 



22 



15 



23 to 28 

 12 to 17 



17 to 21 



