— 
| Theory of Uranus. 237 
The time has now come fora revision of the subject. Con- 
tinued observation has modified essentially the data rs investiga 
tion. From the discussion of ‘six hundred and eighty-nine ob- 
servations, Mr. Walker has diminished the period o Neptune by 
arly two years, and augmented by 48° the longitude of its peri- 
helion. Its miass has also been determined from a satellite with an 
accuracy which M. O. Struve regards as definitive and superior 
to that of the mass of Uranus: thus simplifying the ot apree 
and processes by which our ultimate results‘are derived. That 
these changes would not affect the nature of our eben result, 
could not be confidently decided anterior to trial. We have, ac- 
. cordingly, again attempted te submit to the test’of analysis, the 
ability of the new ‘planet to supply the defects of the Epheme- 
ris, and now propose to give a concise account of the processes 
and results to which we have been conducted. As the latter 
happen to differ essentially from some already before the public, 
it may be proper to add that the liability to etror is very consid- 
erable in inquiries sett such~varied-and extended numerical 
omputations as the prese 
In developing the dietaphing influence ‘of Neptune, we have 
aimed at as high a degree of refinement as seemed to us to ac- 
cord with the present state of its elements. ‘The very considera- 
ble change made in the mean motion by the last reduction ftom 
the observations, seems to indiéate that it is still liable t6 some 
modification ; and it is evidently useless to gather up all the mi- 
nute points of the theory until the ‘data we eee sufficiently 
i to give them significancy and influe 
é fundamental elements employed are es following, © ~ 
a pe a ae Neptune, Jan, 1, 1847, 
Mean Radius ven : : 
Mean motion, : , {596-66 7871'-'76 
Eccentricity, i 0:0466108 0:00857741 
Long. of Perihelion, . 167°-30!-24// 489-21! -3N 
Long. of epoch, : ; 1739-30! 16!" 328°-31'-56!! 
penne i a “+46! 26" 1°-46'-59" 
ong. of Ascen. Node, : 72°-59'- 21" 130° 4!-35/! 
It is important to observe that these’elements of Uranus, with 
a awe apparent exception, ‘are substantially those employed by 
Verrier and Adams in construeting and testing its ephe- 
meris. Both assume 0:046679 for the,eecentricity : but the differ- 
ence between this value and that which we have adopted is alike 
unimportant, in the perturbations and the other terms of the 
equations of condition. Its effect on the principal inequality 
since 1690, and consequently eonfounds itself with the correction 
of the longitude of the epoch. The other term in which its ef- 
fect is most sensible, is that ; aipouting on the difference of the 
Sxconp Serres, Vol. Vj No. 17.—Sept., 1848. a 
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