54 THE ORBIT OF NEPTUNE. 



REMARKS ON THE PRECEDING CORRECTIONS. 



Greenwich. 



The corrections actually applied to the right ascensions from 1848 to 1853 have 

 been derived by comparing the corrections on p. IV. of the introduction to the Green- 

 wich six-year catalogue for 1854 with the corrections given by that catalogue, 

 namely, — 0'.020. From 1857 to 1864 the corrections have been derived in the 

 same way from the seven-year catalogue for 1860. The entire list of corrections 

 is as follows : 



1846, 



-f 0'.044 



47, 



+ 0.059 



48, 



-f .052 



49-55, 



— 0.010 



56', 



— 0.025 



5?^61, 



— 0.008 



62-64, 



+ .002 



The corrections to the declination have been concluded from year to year from 

 the table. 



Cambridge. 



One consistent set of adopted right ascensions having been used in the re- 

 ductions of the Cambridge observations, the constant correction 



— 0».046 



has been applied to the right ascensions throughout. The declinations have been 

 corrected as follows : 



1846-47, — 1".12 



1848-57, — .58 



Washington. 



The corrections to the Washington right ascensions from 1846 to 1850 have 

 been derived from a general comparison of twenty-live fundamental stars near 

 the equator with the results of the Greenwich observations. The mean + 0'.042 

 has been adopted as the constant correction for those years. After 1861, no 

 correction is needed, Dr. Gould's Right ascensions having been adopted in the 

 reductions. 



The corrections to the declinations for 1861 have been derived from those for 

 1862. The latter were diminished by 0".20 for error of nadir point, while no such 

 correction was applied to the former. 



Hamburg. 



Having applied to Charles Ruraker, Esq., M.A., of the observatory at Hamburg, 

 for information respecting the data used in the reduction of the Hamburg obsei'- 

 vations of Neptune, I was informed that both right ascensions and declinations 



