48 °N THE NEW PLANET CERES. 



X. 



* On the new Planet Ceres, 



To Mr. NICHOLSON. 



SIR, Parfon's Green, April 3, IS02. 



The fubject re- Jl\T the conclufion of the memoir concerning the new planet 

 Ceres, which you did me the honour to publifh in your laft 

 number of the Philofophical Journal, a want of Ieifure, and the 

 length of the communication, were alledged as reafons for my 

 not concluding, at that time, the whole of the obfervations 

 which I had to offer on the fubject : I beg leave, therefore, 

 now to refume the examination and detail of thofe particulars 

 which remain yet to be treated of. 

 Difcovery of a About four years ago, when I was inventing a mechanical 

 Sucine the great- contr i vance > by which the equation of the center and true 

 eft equation from diftance of a planet, or any number of planets, might be ex- 

 the eccentricity, hibited in an orrery, I difcovered that the natural fine of half 

 the greateft equation of any planet, is equal, or very nearly equal, 

 to the decimal figures which reprefent the value of a vulgar frac- 

 tion, compofed of the eccentricity and mean diftance of that planet : 

 For inftance, if we take the mean diftance of the earth from 

 the fun at 100000, and the eccentricity, according to Lar 

 lande, at 1681,395, the fraction W-erSlI 5 * converted into a 

 decimal expreflion of the fame value, is 01681395; and, 

 omitting the decimal point and three laft figures, we (hall have 

 01681 for the natural fine of 0° 57' 47,6", which arc differs 

 only about half afecond from one half of the greateft equation, 

 as given in the tables of the third edition of Lalande's Agro- 

 nomy. 



The procefs, in the form of an analogy, will be thus : As 



the mean diftance : is to unity :: fo is the eccentricity : to the 



natural fine of £ the greateft equation. 



Tabulated num- This analogy will apply to all the other planets, as may be 



^rw^nd^ce* feen in the fuD J omed table > which I have calculated from the 



iu all dieplanets. mean diftances and eccentricities given in Lalande's Aftro- 



nomy, and copied by Mr. Vince, except in the inftance of 



Ceres, the data of which planet are taken from the elements 



of Gauls. 



Planets. 



