Royal Astronomical Society. 133 



corrections and the effects of the perturbations, the residual errors are 

 obtained, of which the following are the maximum values : — 



After this time, to the year 1840, the largest error is 2"*35. 

 After 1840, the errors increase on both hypotheses. They are, — 



Hypoth. I. Hypoth. II. 



1843 4-7-11 + 5-77 



1844 + 879 + 7-05 



1845 +12-40 +10-18 



It appears from this extremely probable that the mean distance of 

 the disturbing planet ought to be assumed nearly = mean distance 



of Uranus X . 



0-574 



The residual errors for the single observation of 1690 are, — 



Hypoth. I. H^fpoth- H. 



+ 44"-5 +50"-0 



It seems probable that these errors would be increased by still further 

 diminishing the mean distance. 



Expressions are then investigated for the correction of radius vector 

 produced by the correction of elliptic elements, and by the effects of 

 perturbation. The numerical values are as follows : — 



Hypoth. I. Hypoth. II. 



1834 +0-00505 +0-00492 



1840 +0-00722 +0-00696 



1846 +000868 +000825 



The author states that no satisfactory results could be found for 

 the node and inclination of the planet's orbit, as deduced fronythe 

 irregularities in the latitude of Uranus. 



The author then remarks that the perturbations of Saturn pro- 

 duced by the new planet will be undoubtedly sensible ; and he sug- 

 gests that it would be interesting to examine anew the theory of 

 Saturn, and to ascertain whether the masses of Jupiter and Uranus 

 deduced from it are consistent with those obtained by other methods. 

 He remarks that the published reductions of the Greenwich Obser- 

 vations now make such an inquiry comparatively easy. 



December 14, 1846. — Reappearance of Astraa. 



Extract of a letter from Prof. Schumacher to Mr. Hind, dated 

 Altona, Nov. 27, 1846. 



" M. Otto Struve has already reobscrvcd Astrsea, which ai)pcars 

 brighter than he expected she would. 



