VOL. LXI.] PHILOSOPHICAL TRANSACTIONS. 231 



The 2d column of the '2d table contains the observed duration, or interval of 

 time, between the 2 internal contacts; the 3d contains the difference of each 

 duration, deduced by computation on a supposition that the sun's parallax was 

 = 8".7 on the day of the transit; the 4th, the difference of that duration, as 

 determined by actual observation: In the last column is given the horizontal 

 parallax on the day of the transit, resulting from a comparison of the 3d and 4th 

 columns. In the above comparison he has used Captain Cook's observation at 

 the ingress, and a mean of his and Mr. Green's observations at the egress; 

 because, on a comparison of the observed times at the ingress and egress, made 

 at the several places, when reduced to the centre of the earth, on a supposition 

 that the sun's parallax on the day of the transit was = 8' .65, the difference of 

 meridians, as deduced from Captain Cook's observation at the ingress, agrees 

 much better with the same differences deduced from a mean of the 2 observations 

 at the egress, than those derived either from the observation of Mr. Green, 

 Dr. Solander, or even from a mean of all the 3 observations, as appears from 

 the comparison of them. 



The near agreement of the difference of meridians between King George's 

 Island and the 4 other places, as deduced from Captain Cook's observation at the 

 ingress, and from a mean of his and Mr. Green's observations at the egress, 

 sufficiently shows that the observed duration at King George's Island is at least 

 5^ 29*" 52^5 : and, from a comparison made in the same manner with the 

 observations at Hudson's Bay, it might be shown that the time of the egress is 

 uncertain to a few seconds, owing perhaps to the haziness of the air peculiar to 

 that climate, even at the altitude of 10 or 12 degrees. 



By the end of the sun's eclipse on the morning after the transit, the longitude 

 of Wardhus from Paris, according to Father Hell, is l'' 55"" 6' e. of Paris, or 

 2,h 4m 22^ E. of Greenwich; and, according to the observation of Mr. Ru- 

 mousky, Kola is 2*' 2"' 55' e. of Paris, or 2*" 12"" 11^ e. of Greenwich. The 

 point therefore at King George's Island, where the transit was observed, is 

 9'' 57™ 53^6 = 149° 28' 24* w. of Greenwich; Vill St. Joseph in California is 

 7h IB-" 42-J-' = 109° 40' 37" w. of Greenwich; and Prince of Wales's Fort in 

 Hudson's Bay 6'^ 16 49^^ = 94° 12' 22" w. of Greenwich. 



From the near agreement of the several results before found, which are 

 independent of the knowledge of the longitude of each place, and affected only 

 by the necessary error in observing, the accuracy of the observation made at the 

 Cape of Good Hope in 1761, by Messrs. Mason and Dixon, is abundantly con- 

 firmed; by comparing which with the best observations made in the places whose 

 longitudes were very nearly ascertained, the sun's parallax on the 5th of June 

 was found = 8'.692*. And Mr. Pingre, notwithstanding the several arguments 



