442 



Scientific Intelligence. 



IV. Astronomy. 



1. 



rf his predicted theory of 



tune. — In my communication of the 11th of September last, I showed 

 that the differences between the predicted elements of Neptune, and 

 those which result from observation are inconsiderable. I now propose 

 to go farther into the question, and to prove that all these differences 

 are within the limits which the uncertainty of the data will allow. The 

 discussion will thus terminate with those who seek only for the light. 

 They will reflect, that when an author has brought forth from the data 

 of a question all that is therein contained, nothing more can be asked 

 of him ; and that the more uncertain the data, the more difficult is it 

 to bring out the truth. 



It will be impossible for me to give, in this recapitulation, more than 

 the results of the calculations which served me a basis. These calcu- 

 lations being very extended, I ought simply to lay them before you as 

 matters of demonstration. But nothing would be more agreeable to 

 me than to give conscientiously to each, all the scientific explanations 

 conscientiously asked. 



I. I take up first, the comparison of the true longitude of Neptune, 

 as deduced from my theory, with that which results from the orbit cal- 

 culated by Mr. Walker, from the position of 1795, and upon the obser- 

 vations made during the two last years. This comparison furnishes: 





True longitude in 



True longitude in 



Difference. 





the predicted orbit. 



the orbit of Walker. 



lyiiiv * v^**vw» 



In 1887 



396°-9 415°'5 j 



18 a 6 



1877 



380 -9 393 *6 



12 -7 



1867 



363 9 371*6 1 



7 -7 



1857 



345 7 



349 -7 



4 



1847 



326 5 



327 5 



1 -o 



1837 



306 -4 



305 -7 



-0-7 



1827 



285 9 



283 9 



-2-0 



1817 



265 -3 



262 2 



- 3 1 



1807 



245 2 



240 -7 



-4-5 



1797 



225 9 



219 3 



-6-6 



1787 



207 -6 



198 -0 



-9-6 



| 1777 



190 -4 



176 7 



-13 -7 



! 1767 



174 3 



155 *5 



-18 -8 



The question is, are these differences, thus rigorously calculated for 

 120 years, practically less than those which the uncertainty of the 

 data would and ought to introduce, at one epoch or another. 



First of all, let us understand well, the signification of this expres- 



inn. mu*riMiml- ~f >l„ .;_,_ . __ wh j ch hag tQ0 f ten , 



If any 



m of cne aaia ; an expression 

 through misannrphpnQmn K*o„ la j <en f or uncertainty of the observations. 



- page of the memoir published in 1846* 



he will see that such a substitution of terms was not allowable. 



I will here explain, that the uncertainty of the data, results not only 

 from the uncertainty of the observations, but also from two other causes, 

 viz : 1st, from the possible inaccuracy in the mass of Saturn which 

 may increase the uncertainty of observation 3" : and second, from the 

 influence of a planet situated beyond Neptune, whose effect on Uranus, 





