288 COSMOS. 



has an eccentricity of 0-55, or less than that of the orbits of 

 the two double stars just mentioned. According to Madler's 

 and Hind's calculations, 77 CoronaB and Castor exhibit much 

 less eccentricity, which in the former is 0*29, and in the latter 

 0' 22 or - 24. In these double stars the two suns describe 

 ellipses which come very near to those of two of the smaller 

 principal planets in our solar system, the eccentricity of 

 the orbit of Pallas being 0'24, and that of Juno, 0'25. 



If, with Encke, we consider one of the two stars in a binary 

 system, the brighter, to be at rest, and on this supposition 

 refer to it the motion of the companion, then it follows from 

 the observations hitherto made that the companion describes 

 round the principal star a conic section, of which the latter 

 is the focus; namely, an ellipse in which the radius vector 

 of the revolving cosmical body passes over equal superficial 

 areas in equal times. Accurate measurements of the angles 

 of position and of distances, adapted to the determination of 

 orbits, have already shown, in a considerable number of 

 double stars, that the companion revolves round the princi- 

 pal star considered as stationary, impelled by the same gra- 

 vitating forces which prevail in our own solar system. This 

 firm conviction, which has only been thoroughly attained 

 within the last quarter of a century, marks a great epoch in 

 the history of the development of higher cosmical knowledge. 

 Cosmical bodies, to which long use has still preserved the 

 name of fixed stars, although they are neither rivetted to 

 the vault of heaven nor motionless, have been observed 

 to occult each other. The knowledge of the existence of 

 partial systems of independent motion tends the more to 

 enlarge our view, by showing that these movements are 

 themselves subordinate to more general movements animat- 

 ing the regions of space. 



