MOVEMENTS IN THE STAR-DEPTHS. 65 



recognise stellar rates of motion nearly equalling that 

 at which our earth circuits around the sun. But a 

 velocity which, considered with reference to a minute 

 orb like the earth, is intelligible, becomes altogether 

 startling in the case of orbs like Arcturus and Vega, 

 which undoubtedly exceed our own sun many times in 

 volume. I use the word ' intelligible ' with a purpose ; 

 for I am not considering here what is conceivable or 

 the reverse. We can in reality understand why the 

 earth should be possessed of the velocity she actually 

 displays. We know that the sun's attraction is com- 

 petent to generate such a velocity, or a much greater 

 velocity. But in the case of a star these swift motions 

 cannot be thus explained. The stars are too far apart 

 to be so influenced by their mutual attractions that 

 great velocities would be generated. And thus the 

 thoughtful mind cannot but recognise in the stellar 

 motions a subject of contemplation far more impressive 

 than the subordinate, though even swifter motions of 

 the Earth, Venus, or Mercury. Whence sprang that 

 amazing energy which is represented by the proper 

 motions of the suns ? If we admit the possibility that 

 forces of eruption or expulsion could account for the 

 observed motions, we shall have to answer the startling 

 question, Of what order are the orbs whence the giant 

 suns are expelled ? and the yet more difficult questions, 

 Where are these orbs? and, How is it that, inordinately 

 large though they must be, we are yet unable to distin- 

 guish them from ordinary suns ? If, on the other 

 hand, we prefer to regard the stellar velocities as gene- 



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