^^ 



ASTRONOMICAL. PAPERS. 



5 



'The folloiving Paper by the RevcL Mr. Ewing> *ivns alfo 



i>. 



communicated. 



GENTLE MB N, 



Read June ai, 

 1768. 



A 



S you have taken under confideration, tTie 

 propofat which I made to you the 19th 

 of April laft, of obferving the enfuing Traniit of Venus 

 over the difk of the Sun, which will be on the ^A 

 of June> 1769; permit n;ie to lay before you a pro- 

 jedion of the Tranfit, as feen from Philadelphia, to- 

 gether with the elements of the projedion, deduced 

 from as accurate a calculation as I could make from 

 Dr. Halley's Tables. I find from the obfervations made 

 on the laft Tranfit in June, 17G1, that the mean mo- 

 tion of Venus, for the year 1769, fhouldbe 21" more than 

 thcfe tables make it, and that the place of the nodes of 

 Venus, as ftated ia thcfe tables, needs the following cor- 

 rc£tion. At the time of the ecliptical conjunction of the 

 Sun and Venus in June 1761, their place was 2' 15'' 36' 

 33", and her geocentric latitude was 9' 44.'' .9 fouth. Then 



fay, as 72626.3 the diftance of Venus from the Sun : 

 28894.9 the diftance of Venus from the earth :: 584".9 

 her geocentric latitude : 3' 52".7i her heliocentric latitude 

 at that time. Then fay, as the tangent of the inclination 

 of her orbit with the ecliptic, is to rad. fo is the tangent 

 of her heliocentric latitude to the fine of her diftance from 

 the node; L e. as T, 3° 23' 20": rad, ::T, 3' 52''.7i 



S,i 



-5' 



14", which dedud from her place June 6, 1761 



at the time of the tranfit, viz. at 5 



^7' 



20 at Greenwich; 



and the remainder viz. 2' 14** 31' 19" is the place of her 

 afcending node at that time. The motion of her nodes, 

 as ftated by Dr. Halley, is 31" per annum; therefore, for 

 8 years, add 4' 8'' to the abovementioned place of her 

 node and the fum, viz. 2* 14** ^^' 27'' is the place of the 

 node in the year 1769, June 3d. With thefe correded 

 elements, and others, as in the tables, the followin<r cal 

 culations are made. 



The 



