HimA tava’ Movunrains. 331 
we 
PurTine now tang, 13= gn J * (when f means thie factor, the loga- 
rithm of which is to be found in Table "Ds and substituting this value in 
the preceding, we shall haven 
. D2 Ao? 
di,= ep 3 tang. jp 
LR 2 Cos? Z. 
J’ being rejected from the second member as too small to affect it’s 
value, 
‘Tong. L yx A gue 
di wf ae es ae 
2 RR LR 2 
Now ®*" was originally put equal to = a , Dp hee the number of feet in one 
second of the perpendicular. 
Restoring this value we have 
: ps Tang. Eo A 
es 2 2 Sura ie ai ate 1 
dL = «? f np: Lp:n? Cos “L, 
Tz correction indicated in article 7, “may be easily found as follows: 
It is evident (fig. 1), that 4 D + sine D EA: DE ; sine correction. 
But A D is the radius of curvaturé at 4(). DEA is the Co-latitude 
found by the above for mula, and D E has been shewn, (Art. 8) to be 
equal to 2 eda L, sine 1 Cos @ + 1g L), on account of the smallness of 
the correction we are secking, this is equivalent to 2 e— Cos L putting 
then # = correction sought, and recollecting that sine a" = 5 we shall 
have 
0 Meat \ 
e:.Cos L:: rs : = 
OF M __ 2cab, Cos 2h. 
P 
Tus correction may be taken at once out of Table 7, it is additive as 
. noticed, (Art. 7) to the Co-latitude found by the above, that is subtractive 
ae 
* The value of f, varies of course with that of 9. 
VOL. XIV. 4 Pp 
