THROUGH LIBRARY WINDOWS 267 



among its greatest privileges and highest obli- 

 gations. 



All science is making marked advance, but 

 astronomy is moving at the double-quick. Four 

 hundred years ago Copernicus settled the great 

 principles, and it has never had to beat a 

 retreat; it is rewritten every decade, not for 

 the purpose of correcting material errors, but 

 to incorporate new discoveries that are being 

 rapidly made. Once astronomy treated mostly 

 of tides and seasons and planetary aspects, but 

 these are purely primary matters now; once it 

 considered stars as fixed points of light, now 

 they are suns, carrying their retinue of blazing 

 worlds, and it studies their age and color and 

 relation and movement; once it thought space 

 empty, now it reckons it quivering with force 

 and filled with great suns in motion. Between 

 all suns the vast infinite spaces of ether are 

 more wave-tossed than the wildest storm-swept 

 sea. The telescope is making startling revela- 

 tions of worlds undreamed of, of awful depths 

 and sublime heights and overwhelming systems. 

 The spectroscope is analyzing all starlight and 

 chemically telling its compositon in color and so 

 revealing its chemistry and geology. Multi- 

 plied methods are used to get at their weight 

 and velocity and orbit and perturbations, and 



