40 HISTOKY OF ASTKONOMY. 



pected he saw a second satellite, but was unable to follow 

 it long enough to establish its character. 



The grand question still remains untouched Will the 

 new planet explain the observed irregularities in the motion of 

 Uranus ? 



The planet having been actually discovered in the 

 heavens, by means of certain predicted elements, and 

 within one degree of the predicted place, the natural con- 

 clusion was, that those elements were extremely near the 

 truth, and that the planet would perfectly explain those 

 effects by whose study its own existence had been detect- 

 ed. When, however, observation had rendered it certain 

 that the planet moved in a smaller and less eccentric 

 orbit than had been predicted, it became doubtful 

 whether it would account for the anomalies in the mo- 

 tion of Uranus. When Le Yerrier, in March, 1847, re- 

 ceived notice of the computations of Mr. Walker, who 

 obtained an orbit differing but little from a circle, he at 

 once pronounced the small eccentricity incompatible with 

 the observed perturbations. Mr. Adams, in a letter June 

 llth, 1847, says, "I am hard at work on the perturba- 

 tions of Uranus, in order to obtain a new theoretical de- 

 termination of the place. The general values of the per- 

 turbations are enormous, far exceeding any thing else of 

 the same kind in the system of the primary planets. A 

 comparison of the numerical expressions for the pertur- 

 bations, which I have now obtained, with those which I 

 used before, would justify some skepticism as to former con- 



