176 SCENERY OF THE HEAVENS. 



each other, and have become so close as to present the appearance of a single star to the 

 telescope, their respective motions again opening as it were a breach between them. The 

 constituents of Castor now appear to be closing. " This star," says Sir John Herschel, 

 " seems on the point of undergoing, within the ensuing twenty-four years, a remarkable 

 change, similar to that of which y Virginis has already furnished a striking instance, 

 during the last century, and passing from a distinct double star of the second class to a 

 close one of the first, and ultimately to one of extreme closeness and difBculty, such as only 

 the very finest telescopes, with all the improvements we may expect in them, will be 

 capable of showing otherwise than single." In the following years the distances of the 

 constituents of Castor were as follows : 



1845 - - 3'' -85 I 1854 - - 1" '36 



1848 - -3-37 

 1850 - -2-91 

 1852 - -2-18 



1855 - - -93 



1856 - -0-68 



"We have thus seen suns in motion around each other or around some intervening point, in 

 the case of quadruple and quintuple stars as decisively evidenced by observed pheno 

 mena, as the translation of the distant planets of our system around the central luminary. 

 It required the most acute geometricians to resolve the well-known problem of three bodies, 

 and it may be quite beyond our mathematics to determine the curves described by con 

 nected suns with attendant planets acting and reacting upon each other ; but the fact of 

 the stellar universe being the scene of activities, incessant, complex, yet nicely balanced 

 and harmonised, is clearly before us. 



The contrasted colour of the multiple stars, the rich and varied hues with which they 

 shine, is one of their most striking peculiarities. The stars visible to the naked eye, 

 differ in the tints which they display. This, though very apparent, is not so clearly 

 remarked in our own country by the unaided vision, owing to the general haziness of the 

 atmosphere, as in other parts of the globe. But if we were encamped at night upon the 

 plains of Syria, or on those of High Asia, the greatest projection upon the surface of our 

 planet, where the firmament is displayed with greater clearness through the rarity of the 

 circumambient air, the diverse colouring of the stellar light would be at once observed. 

 Sirius, whose advance to the field of view, on directing a telescope to it, has been likened 

 to the dawn of the morning, is so refulgent that for a time it has been found impossible to 

 endure it, is brilliantly white. There has been some extraordinary changes in the 

 history of this splendid object, for Sirius, now white, was known to the ancients as a red 

 star, and is so characterised by Ptolemy and Seneca. This is not a solitary phenomenon, 

 but one upon which it is quite useless to speculate. Within the last half century y 

 Leonis and y Delphini have very perceptibly changed colour. Lyra, Spica Virginis, 

 Bellatrix, Altair, and Vega are white stars. Procyon and Capella are orange. Al- 

 debaran, Antares, Arcturus, Pollux, and Betelguese are red. The remark has been 

 made by Struve, and it is corsoborated by others, that Herschel assigns to many of 

 the stars a redder tinge than has been verified, arising perhaps from some optical 

 peculiarity, or instrumental defect. It is well known that some persons are unable to 

 discriminate colours correctly, and to certain colours others are totally insensible. 

 The eminent philosopher Dalton belonged to the latter class. He saw no difference 

 between red and green, so that he thought the face of a leaf of laurel a good match to a 

 stick of red sealing-wax. Dugald Stewart also laboured under the same defect. 



"While in many cases the constituents of a binary or multiple system are of the same 

 complexion, and of equal intensity, in other instances, there is a striking diversity as to 

 both. 



