COSMIC PHILOSOPHY 



Huyghens's optical discovery to astronomical 

 observation by Galileo. It was thus with the ap- 

 plication of the isochronism of the pendulum 

 to the making of instruments for the measur- 

 ing of intervals, astronomical and other. It was 

 thus when the discovery that the refraction and 

 dispersion of light did not follow the same law 

 of variation affected both astronomy and physio- 

 logy by giving us achromatic telescopes and mi- 

 croscopes. It was thus when Bradley's discov- 

 ery of the aberration of light enabled him to make 

 the first step towards ascertaining the motions 

 of the stars. It was thus when Cavendish's tor- 

 sion-balance experiment determined the specific 

 gravity of the earth, and so gave a datum for cal- 

 culating the specific gravities of the sun and plan- 

 ets. It was thus when tables of atmospheric 

 refraction enabled observers to write down the 

 real places of the heavenly bodies instead of their 

 apparent places. It was thus when the discov- 

 ery of the different expansibilities of metals by 

 heat gave us the means of correcting our chro- 

 nometrical measurements of astronomical peri- 

 ods. It was thus when the lines of the prismatic 

 spectrum were used to distinguish the heavenly 

 bodies that are of like nature with the sun from 

 those which are not. It was thus when, as re- 

 cently, an electro - telegraphic instrument was 

 invented for the more accurate registration of 

 meridional transits. It was thus when the dif- 

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