CHAP. vi. NEW APPLICATIONS OF LIGHT. 49 



both the visible star and its dark companion are some- 

 what larger than our sun, though of less density; that 

 their centers are 3,230,000 miles apart, and that they 

 move in their orbits at rates of 55 and 26 miles 

 per second respectively; and this information, it 

 must be remembered, has been gained as to objects 

 the light of which takes about forty-seven years to 

 reach us! 



So striking are these results, and so rapid has been the 

 increase in the delicacy and trustworthiness of the obser- 

 vations, that the President of the Royal Astronomical 

 Society, in an address delivered in 1893, contemplated 

 the possibility that, by still further refinements in the 

 application of the spectroscope, the most accurate meas- 

 ures of the rate of motion of our earth in its orbit, and, 

 therefore, of the distance of the sun, might be de- 

 duced from observations of stars which are them- 

 selves so remote as to be beyond our powers of 

 measurement. 



So late as the year 1842 the French mathematician 

 and philosopher, Comte, declared that all study of the 

 fixed stars was waste of time, because their distance was 

 so great that we could never learn anything about them 

 a striking illustration of the complete novelty, no less 

 than of the wonderful possibilities of this marvellous 

 engine of research. ISTot only is it a wholly new depar- 

 ture from anything known or even imagined before, but 

 it is able to give us a large and varied amount of knowl- 

 edge of that portion of the visible universe which has 

 hitherto been the least known and which seemed to be 

 the most hopelessly unapproachable. On every ground, 

 therefore, we must place the discovery and applications 



