THE ORBIT OF URANUS. 125 



rections were applied to his observed times of transit over the mean Avin^ and the 

 resulting time was employed as that of transit. Each time, compared with the 

 computed right ascension of the star gave a value of the clock correction, which 

 was reduced to the time of transit of the planet by tlie hnown daily rate. If tlie 

 instrumental errors were always accurately determined, tlie mean of these clock 

 corrections would be used to obtain the right ascension of Uranus. But it was 

 frequently found that the clock error varied systematically with the declination of 

 the star, so that it was deemed advisable to add to the clock correction a term 

 varying as the simple declination, which was deduced from all the stars, and used 

 to reduce the correction to the parallel of Uranus. 



It was intended to give the results of this reduction for each observation, but 

 on comparing the results with those of Fleming in the Asfro7iOVtische Kuchrlclden, 

 Band 30, it appeared that the results were not materially better than his. It 

 does not, therefore, seem necessary to give more than the mean results for each 

 opposition. 



From Besscl's declinations, with the old Cary circle, I Avas unable to obtain any 

 satisfactory results, owing, apparently, to a want of knowledge of some peculiarity 

 of the instrument. Fleming's reductions were therefore adopted. They are 

 designated bv the letter F in the followin<f list. 



Mean Corrcciluns io ilie Provisional Ephemeris f/iven hy BcsscVn Ohscrvadons at 



Kd/ilijshen/, 1SU-1S29. 



Total numbers of observations, 103. 



ResuUs of Ohscrraflons at various Ol.servatoi-les, from 1827 to 1829 Inclusive. 

 During these three years we have, besides the observations already quoted, the 

 following : — 



1. Observations by Schwerd, at Speier, of which the originals are given in 

 Astronomlsclie BeobacJitnngeii angestdlt aiif der Slermvarte dcs Kiinlijl. Lyzeums in 

 Speyer von F. M. Schicerd, Speyer, 1829-30, and of whicli the reduced results 

 are found in the Astronomische Nachrichten, Band 8, S. 264. 



2. The series by Airy, at Cambridge, commenced in 1828, and found in the 

 Cambridge Observations. 



3. Littrow's Vienna Observations, found in the first series of Annalen der K. K. 

 Slernwarte in Wicn. 



The mean corrections to the provisional eplunncris given by these series are 

 shown in the following table. The observations have been divided in the usual 



