THE STELLAR UNIVERSE. 



(SECOND LECTURE.) 



The extent of the survey of the universe which is commanded by our natural 

 vision, unaided by those expedients which the inventions in optics have sup- 

 plied, has been on another occasion fully explained.* We have shown that 

 objects placed around us within the scope of a radius of such a length that 

 light would take about a hundred and twenty years to move over it, are thus 

 perceivable by us. It does not, however, follow, therefore, that all objects 

 w r ithin that radius are visible. There may be within it stars which fail to be 

 seen ; not because of their comparative remoteness, but because of their com- 

 paratively inferior intrinsic splendor ; and we may infer that interminable 

 realms of space must extend beyond that limit, teeming with innumerable suns 

 and systems, like those which are so abundantly manifested within it. 



An attempt was made by the late Sir William Herschel to ascertain by im- 

 mediate observation the manner in which those stars which are individually 

 visible to us, whether by the naked eye or by the telescope, are distributed 

 through space. Are they casually scattered in all directions, without any 

 definite limit of distance, or any definite form ? Has their entire mass any 

 ascertainable shape or dimensions ? Is it of a regular form, such as a sphere 

 or a cube ? And if it have definite limits, how has it pleased Omnipotence to 

 manifest itself in those unfathomed regions which stretch in all directions 

 around that finite and limited mass of systems ? 



It will be recollected that on a former occasion it was shown, that by the 

 successive application of telescopes of augmented space-penetrating power, 

 we are enabled to bring into view individual stars more and more remote. 

 Denominating the nearest and brightest stars to be at the first order of distance ; 

 those within twice that radius to be in the second order of distance ; those with- 

 in three times that radius to be in the third order of distance, and so on ; the 



* See the lecture on " The Visible Stars." 



