54 oi * THE ^E w PLANET CERES. 



tion of Ceres at 3° 25', we fliall have ?° * 5 '** = 63,83 days 



77° 7376" J 



for the time of continuance in the femicircle embracing the 

 aphelion, longer than in the femicircle which is bife&ed by the 

 perihelion : but if we take the equation at three figns =, 9° 25', 

 fomewhat lefs than the greateft equation, in this cafe, by reafon 

 of the increafed eccentricity, we fhall have the excefs of con- 

 tinuance 9<? 7< >' x } = 175,93 days. 

 77 7376 



Obfervations This fuggeftion may be worthy the notice of the practical 



from which the a ft r onomer : for when a variety of obfervations are taken of 



potion of the 5 .. ...... j, .._ J . _ . . . , 



apfides me de- the new planet in the different quadrants of its orbit, and 

 duced, & c , & c , fa e corre fponding times recorded, it will be no difficult 

 talk, when equidiftant geocentric longitudes are converted 

 into heliocentric longitudes, to obferve what femicircle of the 

 ecliptic correfponds to that half of the orbit in which the pla- 

 net has continued longejl ; the middle of that femicircle will be 

 the aphelion, and the two extremities will be three and nine 

 figns of anomaly : Alfo, the excefs of duration, above the time 

 occupied by the other femicircle, multiplied by the ?nean daily 

 motion, will he four times the equation at three and nine figns 

 of anomaly very nearly ; and as this equation is very little fhort 

 of the greateft equation, the eccentricity may likewife be 

 found by either of the methods already defcribed : Thus the 

 Form and elementary points of the orbit may be gained by a 

 feries of obfervations converted into heliocentric places, even 

 by the projection propofed in the laft memoir on this fubject, 

 and thefe determinations may be corrected by a comparifon of 

 them with the reiults deduced from the properties of an ellipfe, 

 which are here purpofely omitted, left a more minute and 

 fcientific defcription of intricate calculations fiiould rather 

 puzzle than inform the generality of readers*, 

 Inclination of It remains yet that fome obfervations be made relative to 

 the orbit, and the pofition of the orbit of a planet. There are many methods 

 place of nodes. f afcertaining the nodes of a planet's orbit, from calculation 

 grounded upon obfervations ; but the fimpleft, when it is 

 practicable, is to convert the geocentric into the heliocentric 

 place at the time when there is no latitude by obfervation, for 



* See Lalande's and Mr. Vince's Aftronomy ; and alfo ProfefTos 

 ftobifon on the Geo. Sidus, in the Edin. Tranf. vol. I* 1788. 



the 



