224 A CENTURY'S PROGRESS IN ASTRONOMY. 



the Milan Observatory, in the course of a series 

 of star-gauges at the north galactic pole. Using 

 a small refractor, showing stars barely to the 

 eleventh magnitude, he found he could see 

 exactly the same number of stars as Herschel's 

 large reflector, indicating that increase of optical 

 power will not increase the number of stars 

 visible in that direction. Celoria's observation 

 can only be explained on the assumption that 

 the Universe is limited in extent, as otherwise 

 Herschel's telescope should have shown more 

 stars than Celoria's, even granting an extinction 

 of light, a theory which Newcomb, Schiaparelli, 

 and others have shown to be quite untenable. 

 That the Universe is limited in extent is about 

 all that is known for certain, although even this 

 has been called in question, notably by E. W. 

 Maunder and H. H. Turner. The problem of 

 the construction of the heavens is by no means 

 solved, although several more or less probable 

 theories have been advanced. 



A series of investigations on stellar distri- 

 bution, from 1884 to 1898, led Hugo Seeliger, 

 director of the Munich Observatory, to some 

 remarkable deductions. He believes the Uni- 

 verse to be flattened at the galactic poles. The 

 Galaxy is the zone of stellar condensation, and 

 he concludes the distance of the Solar System 



