386 Proceedings of Philosophical Societies, [Ma ♦, 



South Wales, under the direction of Sir Thomas Brisbane, 

 KCB. ; and the application thereof to investigate the exactness 

 of observations made in the northern hemisphere. By the Rev; 

 John Brinkley, DD, FRS." Anxious to throw some new^ hght 

 on the subject of the discordance between the north polar dis- 

 tances of the principal fixed stars, as determined by Continental 

 and English astronomers, Dr. Brinkley wrote to Sir Thomas 

 Brisbane, to request his Excellency to make some observations 

 at Paramatta. Sir Thomas immediately commenced the import- 

 ant labour ; and on a series of three months' observations, from 

 "N^ovember, 1823, to Februaiy, 1824, communicated to this So- 

 ciety as well as to Dr. Brinkley, the Doctor has founded the 

 computations and comparisons which are communicated in this 

 paper. 



The sum of the polar distances of a star observed in the two 

 hemispheres ought to be exactly 180°, if both are correctly 

 observed. xAlso, on the hypothesis that the mean refraction is 

 the same in both hemispheres, we have an opportunity of ascer- 

 taining the united effects of refraction, instead of the difference 

 between the refraction of a star near the pole and of a circum- 

 polar star remote therefrom. 



In regard to the distance between the north and south poles, 

 by combining Dr. Brinkley's observations with those of Sir 

 Thomas Brisbane, the result is that the mean of 141 south polar 

 distances deduced from 141 of his observations, and applied to 

 Dr. Brinkley's north polar distances = 179° 59' 58",92or r',08 

 in defect. Dr. Brinkley's refractions were applied to the south- 

 ern observations, using the interior thermometer. The same 

 mean, obtained by using Mr. Bessel's north polar distances and 

 computing by Mr. Bessel's refractions (Astron. Fundam.), using 

 the ex^mor thermometer, is 180° 0' r',72 or r',72 in excess. 



1°. Among the observations are some by reflection. These 

 afford us the means of determining the zenith point, and thence 

 the distance between the zenith and polar points, or the co- 

 latitude. 



Co-latitude by Cff7AopM5 56° 11' 8'^63 



Sirius 9 ,16 



Fomidhaut 9 ,95 



Mean =56 11 9 ,25 

 Latitude = 33 48 50 ,75 



?° The results of observations on Ao//i the solstices of 1822 

 appear to show the latitude of Paramatta = 33° 48' 42''. — 

 (No. 37, Der Ast. Nachrichten.) 



The observations of the Dec. solstice of 1821 give the mean 

 'zenith distance of the solstial point, Jan. 1, 1822,= 10° 2r2",23. 

 -~(No, 20, Der Ast. Nach.) 



