306 I'be Orbit and Motion of 



V 



its vicinity to the Ecliptic, the direction of its motion, and 

 its being nearly ftationary at the time of its difcovery, in fuch 

 an afpecl: with refpedl to the Sun, as correfponds to the ftation- 

 ary appearance of the Planets. The French aftronomers ima- 

 gined it a Comet, although it had not that train of faint light 

 which ufually diftinguifhes thofe bodies ; and, in the courfe 

 of the year 1781, endeavoured to determine the elements of 

 its motion on this fuppofition, but could not find out fuch as 

 would correfpond with its fuccenlve appearances. They at laft 

 found themfelves obliged to fuppofe, that it moved round the 

 Sun in an orbit nearly circular. Mr LEXEL, Profeflbr of aftro- 

 nomy at St Peterfburg, was the firft who attempted a compu- 

 tation of its motion on this principle j and mowed that a circular 

 orbit, the radius of which is about nineteen times the diftance 

 of the earth from the fun, would very nearly agree with all 

 the obfervations made during the year 1781. The firft diftindl 

 information which I got of it was in June 1782, from Mr MINTO, 

 a gentleman of this place, who communicated to me a feries of 

 excellent obfervations made by Profeflbr SLOP at Pifa. This 

 feries contained the means of determining with accuracy the 

 ftationary points of the Planet in October 1781 and March 

 1782, and its oppofition in December 1781. From thefe, I was 

 enabled to afcertain with great eafe, the radius of its circular 

 orbit. For, at its ftationary appearance, we have the fquare of 



f 2 j 



the cofine of its elongation from the Sun , r being the 



?' 3 T 



J - 



radius, and the earth's mean diftance being i. The oppofi- 

 tion in December 1781, gives us one place of the Planet as 

 viewed from the Sun, independent of all hypothefes. % With 

 thefe data, it was eafy for me to determine the apparent place of 

 the Star for any time, and compare it with obfervation ; and 

 the refult of this comparifon was fuch as to how, that the opi- 

 nion was very nearly true, the greateft errors not amounting 



to 



