Willi A STAR OBSERVED BY LALANDE. 



1 13 



the dates for aberration time, (which amounts to about four hours,) 1 computed the (1.) 

 elements in the table below. The data lor the computation were obtained as follows. 

 The planet's mean place as a fixed star for January 1st, 1817, was derived from the 

 observations. The correction for planetary parallax was applied. The R. A. and Dec. 

 were then reduced to their equivalent geocentric latitude and longitude (a and <$,) referred 

 to the mean equinox of January 1st, 1817, with the mean obliquity. The places arc, 



The smallncss of the values of X — X, and ft' — (3, on which the concluded position of 

 the plane of the whole orbit depends, would have deprived this result of all its value, if 

 the errors of observation had not also been extremely small, so as to bear a correspond- 

 ing proportion to the measured path. There is, however, one advantage accompanying 

 this smallncss ofV — r, viz., that the errors arising from the neglected terms, (the daily 

 variations of r and n,) arc more nearly insensible. 



With the elements (I.) I computed with every possible precision an ephemcris of 

 Leverrier from August 1st, 1846, to February 1st, 1817, and then compared with it all 

 the standard obsecrations yet received, after applying all the small corrections, and trcat- 

 inir 'hem in the same manner as the places of September 2Gth and December 26tb, above. 



The available observations comprehend one hundred and sixteen nights' works in all. 

 They may be thus classified. • 



MERIDIAN OBSERVATIONS. 



