IB35.] Observations on the value of the cipher y^c. 



i)e amiss to observe, that the Astronomer emplbyfed in 

 Interpol atiDQ" *v-o place of the Sun computed to another 

 merio.^ . that of his own, may ascertaiii the 



curac . s calculations in the following manner : — 



Hetaini ' the former notation ~ 



Let S,' denote the A. R. of the mean Sun > on the sue 

 tiie A. R. of the true Sun V ceediag. 



e, the equation of time 5 day. - 



Then we have as before r 

 S' = S ■ — (e -J- acc. e.) . . 



^nd S; = S, -- (e, + acc. e.) 

 S/— S' = S, —S— (e, 4- ace. e.) + (e + acc. e) 



_ S.^ — S — (e, — e) 4- acc. (e, — e) 

 but S/ — S' is the daily variation of the mean Sun=s 3m. 

 56.555s. 



Hence 3m, 56,555 == — S — (e, — e) acc. (e, — e) 

 if the interpolated values of S, — S — &c. satisfy the equa- 

 tion the computer may rely on the accuracy of his cal- 

 culation. ^ ^ I 

 But to proceed on with the inv^tigation r : ; 



Let|^ M be the A. R. of the. planet or Moon 

 M' the same on the succeeding day .- 



ja the difference of the A. R. of the 

 at mean Noon < ^^^^ pj^^^^ 



Moon 



a' the same on the following day 

 d the variation of the difference of 

 the A. R. of the mean Sun arid 

 the planet or Moon 

 t the mean time of transit 



then M — S' =a and 

 M'— S.'=:a' 



— a z=d 



Now if (a) is equal to (a') (t) must also be equal to (a) 

 h^i as this is not the case;, in the time t, a will be alter- 



