SCIENTIFIC PREDICTION 193 



On September 18 Leverrier sent a letter to Dr. 

 Galle, of the Berlin Observatory, which was provided 

 with a set of star maps, prepared at the instance of 

 Bessel. Galle replied one week later. " The planet, 

 of the position of which you gave the indication, 

 really exists. The same day that I received your let- 

 ter [September 23] I found a star of the eighth 

 magnitude, which was not inscribed in the excellent 

 map (prepared by Dr. Bremiker) belonging to the 

 collection of star maps of the Royal Academy of 

 Berlin. The observation of the following day showed 

 decisively that it was the planet sought." It was only 

 57' from the point predicted. 



Arago said that the discovery made by Leverrier 

 was one of the most brilliant manifestations of the 

 precision of modern astronomic science. It would en- 

 courage the best geometers to seek with renewed ardor 

 the eternal truths which, in Pliny's phrase, are latent 

 in the majesty of theory. 



Professor Challis received Leverrier's third paper 

 on September 29, and in the evening turned his mag- 

 nificent refractor to the part of the heavens that Le- 

 verrier had so definitely and so confidently indicated. 

 Among the three hundred stars observed Challis was 

 struck by the appearance of one which presented a 

 disk and shone with the brightness of a star of the 

 eighth magnitude. This proved to be the planet. On 

 October 1 Challis heard that the German observer 

 had anticipated him. 



Arago, while recognizing the excellent work done 

 by Adams in his calculations, thought that the fact that 

 the young mathematician had failed to publish his re- 

 sults should deprive him of any share whatever in the 



