BOUNDARIES OF OUR SOLAR WORLD 311 



had been the essence of the old order of thought. Not 

 long. 



As the wobbling path of the tipsy planet became more and 

 more accentuated, here and there were found minds to throw 

 out a suggestion that the distortions indicated an extra- Uranian 

 body. It was the most obvious explanation, and it presented 

 a beautiful problem. The five or six heavy volumes of the 

 Mecanique Celeste in which Laplace had embalmed the solar 

 system in unchanging stability, were filled with the reverse 

 problem here presented : his task had been to measure the mass 

 of the component members, determine what disturbance each of 

 them would exercise upon the other, then to find if observation 

 agreed with the result. It was by this means that he detected 

 the changing eccentricity of the orbit of the earth. Here the 

 matter was : given a carefully observed disturbance, what and 

 where is the planet, or the planets which cause it ? 



By 1840 the materials were sufficient. Some observers had 

 already thought of a search, in a purely empirical way, for the 

 disturbers. Meanwhile the problem had been independently 

 attacked by two young mathematicians. One was an under- 

 graduate at Cambridge University in England, John Couch 

 Adams ; the other was Urbain Leverrier, in France, friend of 

 the fiery and stimulating Arago. By October 1845, Adams had 

 worked out his results and announced them in a letter to the 

 English Astronomer Royal. The actions of Uranus could be 

 explained by assuming an outer planet which, according to 

 his reckoning, was then moving along at such and such a point 

 in the heavens. So important a post as that of Astronomer 

 Royal must, to be sure, be filled by a personage of distinction. 

 This has its disadvantages. It was Huxley who remarked that 

 the moment a man acquires a great reputation in science 

 he becomes a nuisance. The remark found here an exempli- 

 fication. 



If the Astronomer Royal had pointed his telescope towards 

 the spot indicated by Adams he would have found the new 

 planet within less than a couple of degrees of its calculated 

 location. Instead of that he wrote back a letter with some 

 foolish, vapid questions, quite in the spirit and quite on the 

 customary mental level of official science and official investi- 

 gation of any character whatever. Meanwhile Leverrier was 

 ready with his results ; they were published in June 1846. The 



