ON A CHARGED ELECTRIC CONDENSER MOVING THROUGH SPACE. 
173 
we shall take as 15 miles/sec., OQ is the direction ol drift due to the sun’s annual 
motion, which we take as 19 miles/sec. 
We have, therefore, 
sin V'D _ 1 (, 
sin DQ 
1 5- 
Let V'ND = DNQ = n; then 
sin Yd ) 
sni ui 
sin NW sin V'DN 
Dividing the first by the second. 
and 
sill DD, _ sin n 
sin NO sin NDO 
or 
9 cos 7) sin hi 
^^cos38|- sum 
cos 7) _sin in _ sin m 
•618 sin n sin {in n — m) 
Nov in d- H = V'NQ = + rt — dir), therefore 
cos 7] _ 
sin hi 
sin hi 
•618 sin (^ + a — hir — m) sin + a) sin m + cos + a) cos m 
01 ' 
whence 
sin (^ + a) d- cos (^ + a) cot rn = 
•618 
•618 
cot m = — 
cos Tj cos (f d" 
cos 7 ] 
tan d- «) • • 
. . (iii.). 
From the triangie NDV' 
cos ND cos m = — tan 38d sin ND — cot NDV' sin ni. 
From the triangie NDQ 
cos ND cos n = tan 17 sin ND — cot NDQ sin n ; 
hence, since cot NDV' = — cot NDQ, 
cos N D (cos rn sin n + cos u sin hi) 
= — sin ND (tan 38d- sin n — tan tj sin rn), 
or 
cot ND — h ~ 38-g- (sin »/sin rn) 
~~ — cos (^ d- «) 
sin hi 
cos (^ d- cos 7] 
Now PND = PNV'd- m = On ir - 6 - a). 
(•49 I ~ sin 7]) . 
. . (iv.). 
