426 DISTANCES OF FJXED STARS. [SECT.XXXVII. 



appeared on the 25th of May following would have allowed 

 the globe of the earth to drop through it, leaving a thousand 

 miles clear of contact all around this tremendous abyss. 



Although, from the appearance of the stars, no inference 

 can be drawn as to their distance, yet among the multi- 

 tudes in the heavens, whether double or single, a few are 

 found near enough to exhibit distinct parallactic motions 

 arising from the revolution of the earth in its orbit, from 

 whence their distance from the sun has been computed. Of 

 two stars, apparently in close approximation, one may be 

 far behind the other in space. These may seem near to 

 one another when viewed from the earth in one part of its 

 orbit, but may separate widely when seen from the earth in 

 another position, just as two terrestrial objects appear to be 

 one when viewed in the same straight line, but separate 

 as the observer changes his position. In this case the stars 

 would not have real, but only apparent motion. One of 

 them would seem to oscillate annually to and fro, in a 

 straight line on each side of the other a motion that 

 could not be mistaken for that of a binary system, where 

 one star describes an ellipse about the other, or if the edge 

 of the orbit be turned towards the earth, where the oscilla- 

 tions require years for their accomplishment. 



This method of finding the distances of the fixed stars 

 was proposed by Galileo, and attempted by Dr. Long with- 

 out success. Sir William Herschel afterwards applied it to 

 some of the binary groups ; and, though he did not find the 

 thing he sought for, it led to the discovery of the orbital 

 motions of the double stars. 



Though the absolute distance of most of the stars is 

 still a desideratum, a limit has been found under which, 

 probably, none of them come. It was natural to suppose 

 that, in general, the large stars are nearer to the earth 

 than the small ones; but there is now reason to believe 

 that some stars, though by no means brilliant, are nearer to 

 us than others which shine with greater splendour. This is 



