6 BEYOND THE LIMITS OF VISION. 



telescopic observation. Over five thousand nebulae have already 

 been counted in the heavens ; and every increase in telescopic 

 power not only resolves more of the previously known nebulae 

 into faint clusters of stars, but reveals others still deeper set in 

 the infinitudes of space. Of the nebulous bodies which the 

 Spectroscope has been able to examine, about two-thirds are 

 proved to be clusters of stars, and the other one-third to be gas- 

 eous matter, nitrogen, hydrogen, and an unknown gas, imperfect 

 or new forming worlds. Over three thousand star systems then, 

 probably in every way similar to the one which lights our night 

 skies, have already been located in the outlying regions of space. 

 And still beyond are doubtless other systems teeming with their 

 myriads of self-lighted suns. There is no boundary to the hea- 

 vens. The mind of man cannot conceive of a limit to space. 

 For if there is one, what limits it what is there beyond ? 



The nearest fixed star to us is still twenty million million miles 

 away. Light, which travels at the perfectly inconceivable veloc- 

 ity of 182,000 miles in a second of time, takes three and a half 

 years to come to us from this star, Alpha Centauri. Sirius, the 

 brightest star in the heavens, is separated from us by the light 

 distance of seventeen years or 100 -million million miles. Sir. 

 Win. Herschel estimated that some of the light of the Milky- 

 way is already ten thousand years old when it reaches us. Some 

 of the infinite multitude of stars which appear as the hazy cloud- 

 belt of the Galaxy, emitted the rays which strike our eyes 

 to-night over ten thousand years ago. 



But this is all within our own circumscribed world of worlds. 

 There are telescopic star clusters so far banished in space that 

 they are perhaps to-day receiving the last glimmer of the molten 

 fire beds that once covered our earth. Were the entire stellar 

 universe except our sun and planets swept out of existence at 

 this hour, we would not know it we would not even suspect 

 it for ages to come. 



Such is the infinity of magnitudes. But I will have occasion 

 to-night to speak to you of more startling infinitudes below our 

 sight than there are above it. The world of the infinitely small 

 is of vaster range and set off with far more inconceivable num- 



