THE STORY OF NINETEENTH-CENTURY SCIENCE 



from becoming aggregated into a single body by the 

 perturbing mass of Jupiter. 



As we have seen, the discovery of the first asteroid 

 confirmed a conjecture ; the other important planetary 

 discovery of our century fulfilled a prediction. Nep- 

 tune was found through scientific prophecy. No one 

 suspected the existence of a trans-Uranian planet till 

 Uranus itself, by hair-breadth departures from its pre- 

 dicted orbit, gave out the secret. No one saw the dis- 

 turbing planet till the pencil of the mathematician, with 

 almost occult divination, had pointed out its place in 

 the heavens. The general predication of a trans- 

 TJranian planet was made by Bessel, the great Konigs- 

 berg astronomer, in 184-0; the analysis that revealed its 

 exact location was undertaken, half a decade 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- 



O 



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 Eoyal, 

 and an opportunity was lost which English astronomers 

 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 mathe- 

 matician had placed its hypothetical counterpart. But 

 the search was not made, and while the prophecy of 

 Adams gathered dust in that regrettable pigeon-hole, 

 Leverrier's calculation was coming on, his tentative 

 results meeting full encouragement from Arago and 

 other French savants. At last the laborious calculations 



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