246 THa NEBULAK HYPOTHESIS. 



times the distance of Sirius from the Earth."* And since 

 It is conchided that our Solar System is near the centre of 

 this aggregation, it follows that our distance from the re- 

 motest parts of it is about four hundred distances of Sirius. 

 But the stars forming these remotest parts are not individ- 

 ually visible, even through telescopes of the highest power. 

 How, then, can such telescopes make individually visible 

 the stars of a nebula which is a million times the distance 

 of Sirius ? The implication is, that a star rendered invisi- 

 ble by distance becomes visible if taken two thousand five 

 hundred times further off! Shall we accept this implica- 

 tion ? or shall we not rather conclude that the nebulae are 

 not remote galaxies ? Shall we not infer that, be their na- 

 ture what it may, they must be at least as near to us as the 

 extremities of our own sidereal system ? 



Throughout the above argument, it is tacitly assumed 

 that differences of apparent magnitude among the stars, 

 result mainly from differences of distance. On this as- 

 sumption the current doctrines respecting the nebulae are 

 founded ; and this assumption is, for the nonce, admitted 

 in each of the foregoing criticisms. From the time, how- 

 ever, when it was first made by Sir W. Herschel, this as- 

 sumption has been purely gratuitous ; and it now proves 

 to be totally inadmissible. But, awkwardly enough, its 

 truth and its untruth are alike fatal to the conclusions of 

 those who argue after the manner of Humboldt. Note the 

 alternative. 



On the one hand, what follows from the untruth of the 

 assumption ? If apparent largeness of stars is not due to 

 comparative nearness, and their successively smaller sizes 

 to their greater and greater degrees of remoteness, what 

 becomes of the inferences respecting the dimensions of our 

 sidereal system and the distances of nebulae ? If, as has 



* Cosmos. (Seventh Edition.) Yol. i. pp. 79, 80. 



