r 



NKW, VAK1ABLE, AND COMPOUND STARS. 177 



Among the binary stars catalogued by Struve, the following summary of 596 is given 

 by him : 



Pairs of the same colour and intensity ... 375. 

 Pairs of the same colour, but of different intensity - 101. 

 Pairs of totally different colours .... 120. 



The white stars in the multiple systems are supposed to be 2 times more numerous than 

 the red, and the red twice as numerous as the blue. While insulated stars of a red 

 colour as deep as blood are common in the heavens, and also white and yellow ones, it is a 

 remarkable fact, that no specimen of an insulated blue, green, or violet-coloured star, 

 has yet been found, though these occur in the binary and ternary systems. Struve 

 furnishes the following statement of coloured primaries and blue attendants : 



Pairs consisting of a blue with a white principal star - - 53. 



with a light yellow .... 52. 



with a yellow or red ... 52. 



with a green - .... 16. 



The imagination is apt to run riot, in endeavouring to picture the effect of this variety 

 of colour, to a planetary attendant of one of the suns in a binary or tertiary system. " It 

 may be more easily suggested in words," remarks Sir John Herschel, " than conceived, what 

 variety of illumination two suns a red and a green, or a yellow and a blue one must afford 

 to a planet circulating about either ; and what charming contrasts and grateful vicissitudes 

 a red and a green day, for instance, alternating with a white one and with darkness 

 might arise from the presence or absence of one or other, or both above the horizon." 

 Here we have another example of that beautiful variety combined with evidences 

 of sameness which we encounter in every region of physical nature, and which proclaim 

 its far distant worlds to be the architecture of one infinitely potent and fertile Mind. 

 While the double stars are governed by the same centrifugal and centripetal forces which 

 maintain in harmony our planetary system, they display that diversity of operation in 

 their various hues which is stamped in other forms upon the solar universe. 



From the preceding statements it is clear, as has been previously observed, that the 

 common term, fixed stars, is not rigidly applicable to the bodies so denominated. Orbital 

 revolution is not only displayed by the constituents of the multiple stars, but there are 

 observed instances of a proper motion in space common to the constituents of each. Thus 

 the two stars composing 61 Cygni, have preserved nearly the same distance from each 

 other for fifty years or more, but their common location in the heavens has been altered 

 in that time through an extent of 4''23. The annual proper motion of this double star 

 in right ascension is 5"'46 of space; and in declination 3"-19. The estimated velocity 

 with which it journeys through the vastness of space is supposed to exceed that of the 

 planet Mercury. The two stars, a Ophiuchi and 30 Scorpii, which are 13' apart from each 

 other in space, and which are not orbs revolving around each other, are yet moving 

 along together through the universe, leaving the neighbouring stars behind them. The 

 triple star, p Cassiopeia, has a rapid course through space, at the rate of not less than 

 125,000 miles an hour, and Arcturus has also a considerable proper motion. The 

 change of place in these stars requires perfect instruments, and a lapse of years for 

 their observation ; but a real movement of great magnitude is indicated, of which we 

 should be sensible if we were nearer neighbours to them. In the sixteenth century, 

 Jordano Bruno, an Italian, maintained that we are not warranted in supposing the stars to 

 be all fixed in relation to each other, since their distance from the earth is so immense as 

 to render their motions insensible to us ; and he remarked that it could only be decided 

 after a long course of observation, whether they revolved around each other, or what other 



