26 
MR. POWER ON THE ABSORPTION OF THE SOLAR RAYS, ETC. 
«,= 
■nr 
cos fly * P co cos fl 
that is, 
cos fl ■p i 
COS fly P 
sin 2 (2fl) a 3 6T / 
sin 2 (fl + SyT *fa 
sin 2 (2fl) 1 sin fly 
sin 2 (fl + fly) 1 + s sin 6 ’ 
• 4 cos 2 fl. sin fl. sin fly 
%[ 1+s sin 2 (fl + fl ; ) 
Let us now proceed to the case of the secondary component wave. 
Denoting- by q q' q l the vires vivae of the incident, reflected and refracted rays, and 
by q n the vis viva communicated to the medium, we have 
9 = 2' + ?/ + 9yy; 
and denoting 
we have 
We have, further, 
Consequently 
~ by -s', 
q=q'+(\+s').q r 
2 7T 3 & 2 . 
a— — avco cos 0 
i 2ir-k 1 ' 2 * 
q — — 0 vo) COS 0 
1 a d 
2n 2 /c 2 . 
g,=— ir a ? u cos 6 r 
k^a cos fl k n a cos fl , kfa, cos fl/ 1 + s') 
7a a T" :7a " 7 
with which must be combined, as before, the equation 
k=k'-\-k r 
These equations lead to the same results as before, except that , occupies the 
place of a /5 giving, besides the case of total reflexion, the equation 
Combining with this the equation 
sin 0 = ( 1 +s) sin 0, 
' a. fa 
we get ( 1 +^) sin 0cos 0 (/f-J-A:') = (l +.v').sin 0 t cos 0 l .(k—k l ), 
whence /f'{(l+s) sin 20-j-(l-|-V) sin 20 f) —k. {(1 -\-s') sin 2^— (1 +. 9 ). sin 20}, 
^ (1 +s) sin 26 — (1-fs') sin 26, 
(1 + s) sin 2fl + (I + s') sin 26,’ 
or 
