VOL. LIII,] PHILOSOPHICAL TRANSACTIONS. 23 



to determine the parallax of the sun, by the observation of the late transit of 

 Venus, to be = 10 ', by the observed durations, as well as the least distance of the 

 centres, and by the internal contact at the egress; and seems to think that there 

 must be some mistake in the observation of Mr. Mason at the Cape of Good 

 Hope, particularly with regard to the difference of longitude between Mr. Ma- 

 son's observatory and Paris, because by comparing the observation of Mr. Mason 

 at the Cape with the European observations, he finds the parallax of the sun, 

 thence resulting, to be between S'^andg', consequently differing from the de- 

 termination by the observation at Rodrigues when compared with the same 

 places. Mr. S. therefore in this paper endeavours to prove, beyond all doubt, 

 by a comparison of the observations on this side of the equinoctial line alone, 

 that the sun's parallax is between 8" and Q", and that this determination is the 

 same, or very nearly the same, as when the observation at the Cape is compared 

 with the same places. He also endeavours to prove, that there is a mistake of 

 one minute in time in writing down the time of the internal contact at the egress 

 at Rodrigues, and that this being corrected, the results of the sun's parallax, by 

 a comparison of the observation at Rodrigues with the observations at the several 

 places on this side of the line, is the same with that which results from all the 

 rest; and this agreement is also an argument that there must have been such a 

 mistake in setting down the time of the internal contact at the egress at Ro- 

 drigues. Mr. S. also shows that the parallax of the sun, determined from the 

 observed durations, and from the least distance of the centres, is very nearly 

 the same as that which is determined from the internal contact at the egress, 

 though these last determinations cannot be so much depended on, because of the 

 minute elements from which they are drawn. 



He proceeds to compare the 



, \. c ^u -41 Tobolsk and Abo 3" 4." 37'w. 



observations of the mternal con- Bologna 3 47 46 w. 



tact made on this side of the line Calcutta i 20 38 e. 



only, and thence determines the Calmar "."^ . . ......... 3 27 32 w 



sun's parallax. To do this, it is Cape of Good Hope 3 19 32 w. 



neressarv that the differences of Florence 3 49 3 w. 



necessary inai me ainerences oi Gottingen 3 53 35 w. 



longitude between the places of Grand Mount 46 26 e. 



observation, compared together, groll.": ::;::::::::: I 2? Is I'. 



be well ascertained : and in doing Leskeard 4 5 1 39 w, 



this, in all places ^here the in- ^adras 47 n e. 



' ^ Pans 4 23 51 w. 



gress was observed, he has been Rodrigues o 20 25 w. 



much obliged to a very ingeni- ^°™* ^ *^ ** ^• 



ous method, proposed by M. 



Pingrd in his aforesaid memoir, Tobolsk 



to which Mr. S. refers, and for 



