THE PLANET NEPTUNE. 41 



elusions. But we shall soon see how this great apparent 

 difference affects the result." 



By referring to the table on page 30, it will be seen 

 that Adams and Le Verrier explain the anomalies of 

 Uranus by assuming a very large body (having twice the 

 mass of Uranus) moving in a very eccentric orbit. It is 

 now discovered that the orbit hardly differs at all from a 

 circle, and that the mass is scarcely one half of that which 

 had been assumed. Now the more eccentric the orbit, 

 the greater must be the inequality of a planet's action 

 upon other bodies whose orbits are nearly circular. A 

 considerable part of the observed irregularities in the mo- 

 tion of Uranus, was explained by Adams and Le Verrier, 

 by means of the great eccentricity ascribed to their hypo- 

 thetical planet. This portion is now gone with the failure 

 of the eccentricity. But, on the other hand, Neptune is 

 found to be much nearer Uranus than the hypothetical 

 planet, and in consequence of this proximity, its disturb- 

 ing action is increased, so that these two variations of the 

 elements partly compensate each other. The mass of 

 Neptune is also less than the hypothetical planet of Le 

 Verrier, and on this account its disturbing action is dimin- 

 ished. To what extent the planet Neptune would account 

 for the perturbations of Uranus was not determined until 

 1848. In a communication made to the American Acad- 

 emy April 4, 1848, Professor Peirce announced that the 

 motions of Uranus are perfectly explained, provided we 

 adopt Mr. Walker's orbit, and the mass of Neptune, 

 which is derived from Mr. Bond's observations of Las- 



