DISTANCES OF THE STAB?. 2GS 



No. 1830 of Groombridge, which in France is called Arge- 

 lander's star (with an annual motion of 6 / "'974), are three 

 and four times more distant from the sun than o Centauri, 

 which has a proper motion of 3"-58. Their volume, mass, 

 intensity of light, 17 proper motion, and distance from our 

 solar system, stand in various complicated relations to each 

 other. Although, therefore, generally speaking, it may be 

 probable that the brightest stars are nearest to us, still there 

 may be certain special very remote small stars, whose photo- 

 spheres and surfaces, from the nature of their physical con- 

 stitution, maintain a very intense luminous process. Stars 

 which from their brilliancy we reckon to be of the 1st magni- 

 tude, may be further distant from us than others of the 4th, 

 or even of the 6th magnitude. When we pass by degrees 

 from the consideration of the great starry stratum of which 

 our solar system is a part, to the particular subordinate sys- 

 tems of our planetary world, or to the still lower systems of 

 Jupiter's and Saturn's moons, we perceive central bodies 

 surrounded by masses in which the successive order of 

 magnitude and of intensity of the reflected light does not 

 seem to depend on distance. The immediate connexion sub- 

 sisting between our still imperfect knowledge of parallaxes, 

 and our knowledge of the whole structural configuration of the 

 universe, lends a peculiar charm to those investigations which 

 relate to the distances of the fixed stars. 



Human ingenuity has invented for this class of investiga- 

 tions methods totally different from the usual ones, and which, 

 being based on the velocity of light, deserve a brief mention 

 in this place. Savary, whose early death proved such a loss 

 to the physical sciences, had pointed out how the aberration of 

 light, in double stars, might be used for determining the paral- 



27 On the proportion of the amount of proper motion to 

 the proximity of the brighter stars. See Struve, StclL. 

 compos. Mensurce microm., p. clxi>. 



