VOL. LII.l PHILOSOPHICAL TRANSACTIONS. 599 



fore, as seen from the centre of the earth, was at 21^ 6*" 28^, and the external 

 contact was at 21^ 23"' 25% and the egress of the planet's centre at 21^ 14m 33^ 



From the time of the planet's passage over the edge of the sun's disk, as seen 

 from the earth's centre, the author very accurately determines the planet's diame* 

 ter to be 57%. 



The egress of the centre of Venus, as deduced from the position of its path, 

 and from the other elements as related above, differs near 2 minutes from the ob- 

 served time, when corrected by parallax, and reduced to the earth's centre. This 

 difference is entirely to be attributed to an error in the motion of Venus in longi- 

 tude, which perhaps could not be deduced with sufficient accuracy from these 

 observations, and from a small error in some of the other elements ; all which 

 the author might have taken with the utmost accuracy from the tables either of 

 Dr. Halley or M. Cassini. Perhaps also some part of this difference might arise 

 from our ignorance of the true quantity of the sun's parallax. 



Hitherto our author has given us those elements which might immediately be 

 determined from his observations : the following are deduced from the tables. 

 From the motion of Venus in latitude, it may readily be collected, that the planet 

 was in its node on June 5, at 14^ 55"^ 9^ The place of the sun at that time, 

 according to the tables of the Abbe De la Caille, was in n 14° 59' 5"-l ; and the 

 planet's elongation from the sun at the same time was 1° O' 58'. Therefore 

 the longitude of Venus, and also of the node, was in n 13° 58' 7''i-. The angle 

 at the sun or the difference of the longitude of the planet and the earth, as seen 

 from the sun, was 0° 24' 15" Therefore the longitude of the descending node of 

 Venus as seen from the sun, was in ^ M*^ 34' SC. 



The latitude of Venus as seen from the earth, at the time of the conjunction, 

 was O^ 9' 27'''!-; by solving a triangle of which the computed distances of the 

 earth and Venus from the sun constitute 2 sides, the angle at the sun, or the 

 planet's heliocentric latitude, viz. 0° 3' 46', will be determined. With this 

 heliocentric latitude, and the calculated place of the sun at the time of the con- 

 junction, and the longitude of the node, as before laid down, from two sides of a 

 spheric right angled triangle, an angle may be computed which will express the 

 inclination of the planet's orbit with the ecliptic. The place of the sun at the 

 time of the conjunction, was in n 15" 36' 10'. The difference of the heliocen- 

 tric longitude of the earth and the node was l'' I' 20''. Therefore the angle of 

 the inclination of the orbit of Venus with the ecliptic is 3"^ 30' 49'. 



N. B. The several numbers contained in this paper, are taken from the correct 

 numbers written in the margin of the printed memoir, with the author's own 

 hand, and which seem to be the result of his latest calculations. And though 

 his observations were made with great care, and faithfully calculated, yet the re- 



