A HISTORY OF SCIENCE 



ed from becoming aggregated into a single body by the 

 perturbing mass of Jupiter. 



The Discovery of Neptune 



As we have seen, the discovery of the first asteroid 

 confirmed a conjecture; the other important planetary 

 discovery of the nineteenth century fulfilled a predic- 

 tion. Neptune was found through scientific prophecy. 

 No one suspected the existence of a trans-Uranian 

 planet till Uranus itself, by hair-breadth departures 

 from its predicted orbit, gave out the secret. No one 

 saw the disturbing planet till the pencil of the mathe- 

 matician, with almost occult divination, had pointed 

 out its place in the heavens. The general predication 

 of a trans-Uranian planet was made by Bessel, the great 

 Konigsberg astronomer, in 1 840 ; the analysis that re- 

 vealed its exact location was undertaken, half a dec- 

 ade later, by two independent workers John Couch 

 Adams, just graduated senior wrangler at Cambridge, 

 England, and U. J. J. Leverrier, the leading French 

 mathematician of his generation. 



Adams's calculation was first begun and first com- 

 pleted. But it had one radical defect it was the work 

 of a young and untried man. So it found lodgment in a 

 pigeon-hole of the desk of England's Astronomer Royal, 

 and an opportunity was lost which English astrono- 

 mers have never ceased to mourn. Had the search 

 been made, an actual planet would have been seen 

 shining there, close to the spot where the pencil of the 

 mathematician had placed its hypothetical counter- 

 part. But the search was not made, and while the 

 prophecy of Adams gathered dust in that regrettable 



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