204 History of the Discovery of the Planet Neptune. 
Le Verrier, in March, 1847, received notice of the computations 
of Mr. Walker, who obtained an orbit differing but little froma 
circle, he at once pronounced the small eccentricity zcompatible 
with the observed perturbations. Mr, Adams, in a letter of June 
11, 1847, says ‘Iam hard at work on the perturbations of Ura- 
nus, in order to obtain a new theoretical determination of the 
place. The general values of the perturbations are enormous, 
far exceeding any thing else of the same kind in the system of 
the primary planets. A comparison of the numerical expressions, 
or the perturbations which I have now obtained, with these 
which I used before, would justify some skepticism as to former 
conclusions. But we shall soon see how this great apparent dif- 
ference affects the result.” 
y referring to the table on page 195, it will be seen that 
Adams and Le Verrier explain the anomalies of Uranus, by assum- 
lug a very large body (having twice the mass of Uranus) moving 
ina very eccentric orbit. It is now discovered that the crbit 
hardly differs at all from a circle, and that the mass is only about 
one half of that which had been assumed. Now the more eccen- 
tric te orbit, the greater must be the inequality of a planet’s ac- 
tion upon cther bedies; that is, the greater the perturbations it 
must cause in their motions. One half of the observed irregularity 
in the motion of Uranus, was explained by Adams and Le Verrier 
by meaus of the great eccentricity ascribed to their hypcthetical 
planet. This half is now gone with the failure of the eccentric- 
ity. Buton the cther hand, Neptune is found to be much nearer 
Urauns thay the hypothetical planet, and in consequence of its 
proximity its disturbing action is increased, so that these two va- 
riations of the elements in a measure ecmyensate each cther. 
But it is also discovered that the mass of Neptune is materially 
less than the hypcthetical planet of Le Verrier, and on this ac- 
count its disturbing action is, diminished. To what extent the 
planet Neptune will account’ for the perturbations of Uranus can 
ouly be determined by a rigeroys and careful computation. But 
this computation invelves no new theoretical difficulty. We 
now kuow the mass of Neptune and its orbit; and we can em- 
ploy the same methods which have long been practiced in the case 
of the other planets. ‘The methods of computation are well 
known, but the 0) eration is laborious. Messrs. Peiree and Adams 
are now vecnpied with this problem, and it is presumed Le Ver 
rier also; but the results of their labors are yet only partially 
known. It is understood that Prof. Peirce has found it impessi- 
ble to explain the whole perturbation of Uranus by the action of 
Neptune. 
On the whole then we seem authorized to conclude, that the 
planet Neptune is not the hypothetical planet of Le Verrier, and 
for the following POMONES yond each (otic ioe 
Wee eile ‘ 
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