714 PHILOSOPHICAL TRANSACTIONS. [aNNO 1743. 



ing to which, if we suppose the central ingress to have been at 4'' 57™, we shall 

 find the difference of longitude at that time 3' 20" ; and the semidiameter of 

 the sun being 15' 57", the latitude of Mercury must be 15' 36", Now the 

 angle of Mercury's visible way with the ecliptic being, by the theory of his 

 motion, 10° 12,' , we must conclude the former of the observed latitudes about 

 4" too small, and the latter as much too large; — an error very inconsiderable in 

 this kind of observations. From these things we may gather by an obvious 

 computation, that Mercury was in conjunction with the sun, in respect of 

 longitude, at b^ 47™, with 14' 59" north latitude ; and that his nearest distance 

 to the centre of the sun was 14' 44"; and when he was at his nearest distance, 

 the difference of his longitude from the sun's was l' 39", which he passed over 

 in 40™ of time, and consequently arrived at the middle of his course in the sun 

 at &" 27™ '. whence the semiduration of the central transit was 1*" 30™, and the 

 end at 7'' 57", an hour after son-set. 



As to the lunar eclipse, Dec. 24, 1740, the sky was unfavourable from clouds. 

 However the following observations may be depended on. 



At b"^ 24™ A plain penumbra, apparent time. 



5 35 The true shadow seems to enter. 



8 30 End of the eclipse. 



OJ the Transit of Mercury over the Sun, Oct. 2b, J 743, in the Morning, 

 observed at Mr. Geo. Graham's House in Fleet-street. N° 471, p. 578. 



The beginning could not be seen for clouds; but about 8'' 45™, Mercury was 

 seen (through a reflecting telescope 3-foot focus, magnifying about 50 times) 

 about 4 or 5 of his diameters within the sun's limb. 



At Mr. Short's house in Surrey-street, Mercury was seen just past the in- 

 terior contact at 8'' 30™ 59% through a reflecting telescope 2-foot focus, magnify- 

 ing about 70 times; the person who observed it says, that the thread of light be- 

 tween Mercury and the sun's limb was so small, as scarcely to amount to the 

 20th or 30th part of Mercury's diameter. 



Mr. Graham got an observation made by a person in his neighbourhood, by 

 which it appears, that at 1 1** 59™ 50*, Mercury preceded the sun's centre 42* in 

 right ascension. 



The sky clearing up towards 1 o'clock, the following times were observed at 

 Mr. Graham's house with great accuracy. 



Last interior contact at l*" O™ 42* 



End, or Mercury just leaving the sun's limb at 1 2 l6 



This last observation agrees to a second with the same observation made by 

 Dr. Bevis at Mr. Sisson's house in the Strand. 



I ' 



