THE STORY OF NINETEENTH-CENTURY SCIENCE 



struments the old and almost infinitely difficult problem 

 of star distance was solved. In 1838 Bessel announced 

 from the Konigsberg observatory that he had succeeded, 

 after months of effort, in detecting and measuring the 

 parallax of a star. Similar claims had been made often 

 enough before, always to prove fallacious when put to 

 further test; but this time the announcement carried 

 the authority of one of the greatest astronomers of the 

 age, and scepticism was silenced. 



Nor did Bessel's achievement long await corrobora- 

 tion. Indeed, as so often happens in fields of discov- 

 ery, two other workers had almost simultaneously 

 solved the same problem Struve at Pulkowa, where 

 the great Russian observatory, which so long held the 

 palm over all others, had now been established ; and 

 Thomas Henderson, then working at the Cape of Good 

 Hope, but afterwards the Astronomer Royal of Scotland. 

 Henderson's observations had actual precedence in point 

 of time, but Bessel's measurements were so much more 

 numerous and authoritative that he has been uniformly 

 considered as deserving the chief credit of the discovery, 

 which priority of publication secured him. 



By an odd chance, the star on which Henderson's ob- 

 servations were made, and consequently the first star the 

 parallax of which was ever measured, is our nearest 

 neighbor in sidereal space, being, indeed, some ten bill- 

 ions of miles nearer than the one next beyond. Yet 

 even this nearest star is more than 200,000 times as re- 

 mote from us as the sun. The sun's light flashes to the 

 earth in eight minutes, and to Neptune in about three 

 and a half hours, but it requires three and a half years 

 to signal Alpha Centauri. And as for the great major- 

 ity of the stars, had they been blotted out of existence 



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