38 On a supposed Alteration of Aberration of Light fyc. [Nov. 23, 



Day of 

 observation. 



Star's 

 Observed 

 Zenith- 

 distance 



North. 



Star's Declina- 

 tion from 

 4 Nautical 

 Almanac.' 



Difference for 

 Geographical 

 Latitude of 

 Instrument. 



Correction 

 for Aberra- 

 tion adopted 

 in ' Nautical 

 Almanac' 



1871. 



Feb. 28 



March 1 



3 



4 



16 



17 



21 



23 



24 



26 



27 



85-30 

 85-71 

 84-19 



82- 18 



83- 63 



84- 58 



83- 87 



82- 73 



84- 18 

 84-04 



83- 48 



5°1 29 59-3 

 59-1 

 58-9 

 58-8 

 58-0 

 58-0 

 57-9 



57- 9 



58- 

 58-1 



51 29 58-2 



5°1 28 34-0 



33- 4 



34- 7 

 36-6 



34- 4 

 33-4 

 340 



35- 2 

 33-8 

 341 



51 28 34-7 



-18-71 



18- 82 



19- 02 

 19-11 

 19-73 

 19-74 

 19-73 

 19-69 

 19-66 

 19-59 



-19-54 



Mean Latitude of Instrument from j ^ g . 





Aug. 29 



Sept. 5 



7 



9 



11 



15 



17 . 



22 



24 



Oct. 1 



2 



3 



4 



6 



122-10 

 121-84 



121- 62 



120- 27 



122- 98 

 122-20 



121- 53 

 121-38 

 120-01 

 120-62 



120- 29 



121- 31 

 124-41 

 120-60 



51 30 34-4 

 35-0 

 35-1 

 35-2 

 35-3 

 35-4 

 35-5 

 35-5 

 35-4 

 35-1 

 35-1 

 35-0 

 34-9 



51 30 34-8 



51 28 32-3 

 33-2 



33- 5 



34- 9 



32- 3j 



33- 2 



34- 



34- 1 



35- 4 

 34-5 

 34-8 

 33-7 

 30-5 



51 28 34-2 



4-18-25 

 1901 

 19-18 

 19-33 

 19-45 

 1964 

 19-70 

 19-74 

 19-72 

 19-46 

 19-40 

 19-33 

 19-26 



4-19-10 



Mean Latitude of Instrument from ' 

 Autumn Observations J 



. 51 28 33-6 





Remarking that the mean results for Geographical Latitude of the Instru- 

 ment (determined from observations made when the Aberration of the star 

 had respectively its largest + value and its largest — value) agree within a 

 fraction of a second, I think myself justified in concluding that the hypo- 

 thesis of Professor Klinkerfues is untenable. Had it been retained, the 

 Aberrations to be employed in the corrections would have been increased 

 by +15" and — 15" respectively, and the two mean results would have dis- 

 agreed by 30". 



The latitude of theinstrument from these observationsis about 5 1° 28' 34"*0. 

 The position of the instrument, as measured on the Observatory Map, 

 is 340 feet south of the Transit-circle, a spatial distance correspond- 

 ing to about 3"-35. The latitude of the Transit-circle being taken at 

 51° 28' 38"-4, the geodetic latitude of the instrument is 51° 28' 35"'05, 

 an agreement closer than I expected, consideration being given to the form 

 of the ground. It appears very probable that at the place of the Transit- 



