94? Mr. Ivory on the Theory of the Astronomical Refractions, 
ui\+a) ^ \ . da \ di\ ^ 
S3 + rf.89 = sin9x -g.— J-S 
+ 
de dS 
+ 
e 
d\ 
de 
Now 
wherefore, 
8 0 4-6? 
.xQ,} 
de ^ 1 
e ~~ 2 
d K 
~ 
di 1 — 
i • r+7"’ 
du di ^ 
a i 
d 
— sin 
di, S 
(- 
V 9. 
£S 
1 4- ^ 
4- sin 
g “ +^) /6?« 
' V 5i ' ^ ^ i * 
K Qj . 
If y denote the observed height of the barometer, reduced 
to the fixed temperature of 50° Fahr.; and t the temperature 
of the air on the same scale ; then (3 = 
480’ 
P 
6?« _ 1 
^ a “ 1 4-/3 (t— 50)’ 30 
d a 
a 
d i 
i 
d a 
t~50 
= + 
480 
T— 50 
~^480 
30— p 
30 ’ 
— — 2 ^ 
a T ~ ^ ~480 
50 30— 
30 
These values being found, if we put 
« (1 4-a) 
dS 
a/ 5i " 480 V— 
4-2xQ 
T = sin 0 X X 7^ X , 
2(l+e2) 
. a(l-l-a) 2xQi 
^ ^ fw"" 
the expression of the mean refraction with its correction will 
be as follows. 
