THE STORY OF NINETEENTH-CENTURY SCIENCE 



infinite ocean of space. So distant from our universe 

 are these ne\v universes of Herschel's discovery that 

 their light reaches us only as a dim nebulous glow, in 

 most cases invisible to the unaided eye. About a hundred 

 of these nebulae were known when Herschel began his 

 studies. Before the close of the century he has discov- 

 ered about two thousand more of them, and many of these 

 had been resolved by his largest telescopes into clusters 

 of stars. He believes that the farthest of these nebulas 

 that he can see is at least 300,000 times as distant from 

 us as the nearest fixed star. Yet that nearest star is so 

 remote that its light, travelling 180,000 miles a second, 

 requires three and one-half years to reach our planet. 



As if to give the finishing- touches to this novel 

 scheme of cosmology, Herschel, though in the main 

 very little given to unsustained theorizing, allows him- 

 self the privilege of one belief that he cannot call upon 

 his telescopes to substantiate. He thinks that all the 

 myriad suns of his numberless systems are instinct with 

 life in the human sense. Giordano Bruno and a long 

 line of his followers had held that some of our sister 

 planets may be inhabited, but Herschel extends the 

 thought to include the moon, the sun, the stars all the 

 heavenly bodies. He believes that he can demonstrate 

 the habitability of our own sun, and reasoning from 

 analogy, he is firmly convinced that all the suns of all 

 the systems are " well supplied with inhabitants." In 

 this, as in some other inferences, Herschel is misled by 

 the faulty physics of his time. Future generations, work- 

 ing with perfected instruments, may not sustain him 

 all along the line of his observations even, let alone his 

 inferences. But how one's egotism shrivels and shrinks 

 as one grasps the import of his sweeping thoughts ! 



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