The Milky Way 



at the Lick observatory, in the form of a large 

 reddish star, whose weak light is lost in the 

 radiant brightness of Procyon. 



We have mentioned these two examples in 

 which theory owed its confirmation to the 

 chances of observation, because the companions 

 of Sirius and Procyon happened not to be 

 completely extinct. But many other cases exist 

 in which an equally reliable interpretation is 

 possible. The Star C of Cancri progresses 

 on the average in the sky at the yearly rate of 

 one half degree, but this displacement is any- 

 thing but regular. Every eighteen years a 

 sensible backward motion takes place, lasting 

 about two years. It has been possible to ex- 

 plain this anomaly by the existence of a dark 

 companion, whose elements have been determined 

 by the perturbations of star C. The astronomy 

 of the invisible has thus its own method, which 

 is truly slow and tentative, but sure in principle 

 and rich in results. 



The discoveries of astronomy have revealed 

 to us the multiplicity of the forms which people 

 the universe. They show us a world which is 



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