JUPITER. 



Exaniple. — To fnd the trui heliocentric Latitude and Lon/ttude cf Jupiter, on July li, 17S0, at f' 49' mean 7~:ir 



at Greenivich. 



This is the true heliocentric longitude on the ecliptic, 

 from the mean equinox ; and if we want it from the true 

 equinox, we muft apply to it the equation of the equi- 

 noxes. 



In this operation, the firft five lines are taken out im- 

 mediately from the Tables. The great equation is thus 

 found: for the beginning of 1780 it is 20' 46", as found 

 immediately in the Table. The great equation for a very 

 Uiftant period is thus found : the variation is cxprefled by 

 - a X o'. 042733 X fin. (5 5 - 2 / r 5° 34' 8" - a X 

 58".88) ; if we take a - 459.38, which is li:.if a period, 

 a X o".042733 = 19.'6, which ia additive i^ir*- 1750; this 

 then is the greatell variation of the equation, taking $ S — 



2 / 4- 5' 34' 8 ' — a X 58".8S = 90", fo that its fine may 

 = I, a maximum ; that is, it is the variation anfworing to 

 the prcfent greateft equation 2c' 49'. 5, for this is the greatcd 

 equation when a = o, or for 1750, and therefore will be 

 very nearly fo for the prefent time. Now fuppofe we 

 wanted to know the equation for May l6, in the year 133, 

 or in the year 133.37 ; then we multiply a half period by 

 fuch a number, that the produd added 10 133 may produce 

 fome year in our Table VI., and then we find ihe equation 

 for that year ; multiply therefore 45Q 38 by 4, and add it 

 to 133, and it gives 1970, correfpoiiding to which, the equa- 

 tion IS 6' 40 '.2 ; now tiic variat:on -of the greatell equation 

 is I9''.6 for half a period, and therefore it is 4 x iy'.6 = 



78".+ 



