ON THE PICKET CERES* 291 



The reafon of drawing the occult parallel lines, which may by projeaion is 



not occur to the reader, is this; as the ecliptic is confidered curate . an ^ 



to be an infinite diftance, i'o that the whole otbit of the earth, new. 

 if feen from it, would appear only as a point, a line drawn to 

 it from the fun, and another parallel thereto from the cir- 

 cumference of the earth's orbit, will, to an eye placed in the 

 ecliptic, even if it were only at the diftance of a liar, appear 

 coincident on the fame line ; hence if a line be drawn from the 

 earth to the planet in its orbit, let their refpective iituations 

 be what they may, another line drawn parallel to that from 

 the fun, till it reaches the ecliptic, will mew the geocentric 

 meafure therein the fame as if that meafure were taken in a 

 graduated ecliptic defcribed from the earth as a center, and 

 having all its divifions exactly parallel to thofe of the ecliptic 

 defcribed from the fun as a center. 



Indeed, I have tried this projection with the geocentric Tried with the 

 and heliocentric places of fome of the other planets taken ~* ot er pla- 

 from an ephemeris, and find it extremely accurate as well as 

 ea/y. 



From this projection of the heliocentric and geocentric Remarks from 

 places of Ceres, it appears evident that the diftance from the ^ rdative°mo- 1 

 earth to it was much greater laft fummer when the earth was tions and appa- 

 at P, than it is at prefent, and it is equally evident, that as ^h^Yan^* 

 the velocity of the earth is greater than that of the new planet, 

 and as they were both moving in the fame direction at the 

 latter period in the projection, the diftance will continue to 

 diminifh until both the planets are in the fame ftrait line as 

 feen from the fun, agreeably to what is faid in the extract from 

 Von Zach's letter; for the apparent magnitude is in an in- 

 verfe ratio of the diftance, fo that as the diftance diminiines, 

 the apparent difk increafes. The reafon alfo appears clear, 

 why there was very little apparent motion of the new planet 

 in the laft month as feen from the earth, for in this part of the 

 earth's orbit Ceres would appear to have a retrograde motion, 

 provided it were at reft, but its forward motion in a certain 

 degree balanced that, and produced the effect of little or no 

 apparent motion at all : — on the 6th or 7 th of Feb. laft it was 

 ftationary, and lias been fince retrograde in a fmall degree. 



U2 In 



