ASTRONOMICAL UISCOYKRIES. 35 



tions of Uranus which could not be referred to the disturbing influence 

 of Jupiter and Saturn. This want of agreement between theory and 

 observation was attributed by some to errors in the mathematical pro- 

 cesses by which astronomers have determined the longitude which, ac- 

 cording to theory, Uranus ought to have; but M. Le V., after a rigid ex- 

 amination, found those calculations correct, and hence concluded that 

 Uranus must be exposed to the influence of an exterior planet. He now 

 conceived the bold and original design of determining solely by mathe- 

 matical investigations what the position and mass of this body must ne- 

 cessarily be in order to account for those mysterious perturbations. 



The planet Uranus, before it was shown to be a member of the so- 

 lar system, had been frequently seen by Flamstead, Lcmonnier, and 

 other astronomers, by whom it had been classed with the fixed stars. — 

 Le Verrier made use of all these lecorded observations, comparing the 

 places of the planet thence deduced, with those which it ought to have 

 had by theory at the same epochs, hi like manner he availed himself 

 of all the observations of the planet, made at Paris and Greenwich, from 

 1781 to 184-5. This Herculean task having been completed, the result 

 was submitted to the Paris Academy of Sciences, on the oOth of June, 

 1846, in a paper which, at the lime, attracted much attention. But, al- 

 though the utmost confidence was expressed by the author in the cor- 

 rectness of his deductions; although the elements of the orbit of his 

 unseen planet were given, and the place in which it was to be looked 

 for designated ; perhaps few, if any, expected his calculations to be ver- 

 ified by observation. 



When the existence of the new planet was announced, its position 

 was such that it could not be ob.served ; but about two months subse- 

 quently M. Le Verrier by letter requested Dr. Galle, of Berlin, to exam- 

 ine with his telescope, the portion of the heavens in which the planet, 

 as he said, was situated ; and on the 23d of September, the Doctor actu- 

 ally discovered, in the region assigned by Le Verrier, a star of the eiglilii 

 magnitude not marked on the map. This he immediately suspected to 

 be the looked-for planet, and, on the following evening his suspicion 

 was confirmed by observing that it had moved from its former place, so 

 that its motion, both in direction and distance, was precisely such as was 

 required by the elements of the planetary orbit computed by Le Ver- 

 rier. It was observed in London, on the night of September 29th, and 

 has since been seen at the different Observatories in our own country. 



The distance of the new planet from the sun is thought to be about 

 twic'c that of Uranus. According to Bode"'s law, it would be rather 

 greater, or 3,086,000,000 milea, and this is probably very nearly the true 



