DIURNAL VARIATIONS OF TERRESTRIAL MAGNETISM. 
53 
previous investigation the calculation was carried as far as a/ and a 2 for the law 
K (a d + aq cos w + a 2 cos 2 w), but this degree of approximation proves to be insufficient 
for the purposes of this paper. The terms have therefore been computed as far as 
the fourth order, for the same law and for the atmospheric oscillation Q 2 2 . In this 
case (58) takes the form 
(61) 24#, sin 2 8 cos 0 = 2 2 p m n R ;) ” (s'). 
The values of the more important coefficients p m n calculated from this equation are 
given in the following table :— 
Table O. 
Annual terms —- 
P 2 — — cq cos $ + - ---- - a Y cos S (2a/—9a.,) (5 cos 2 (5—4 sin 2 (5) 
63 1134 
p., 1 = 
Pi = 
a/ cos 3 d -f— a Y a 2 cos 3 S 
189 
2 1 
42 
15 270 Ul + 45 ° J * 24.81 ^ V32 
+ ■ - 1 ai 2 a 2 (59 cos 4 (5—8 sin 2 $ cos 2 (5+80 sin 4 (5) 
1o.810 
— —^— a 2 2 (l 1 cos 4 <$—8 sin 2 $ cos 2 (5+16 sin 4 S) 
2700 “ 
ft " != wH8-0 ai ‘“ S ‘ 4+ 5l0“ /0OS<i 
■ a. 
— cos 4 (5+ — sin 2 S cos 2 <5+ — sin 4 S 
20 5 
3 1 « , 1 
Pi — 777: a \ cos o + 
140 
2100.240 
Pi= 0 
4 — —-— a., cos 2 <5 + 
P5 3150 
Pf 4 = 0 
1 
600.9450 
«! cos &(lba/— 64a 2 ) (4 cos 2 (5 —sin 2 S) 
(I0a/ — 51a/a 2 + 40a/) cos 2 S (3 sin 2 (5 — 2 cos 2 S) 
Seasonal terms — 
2 i 
pi 1 = Ct 2 sin <5 COS S- —— a 4 sill S cos 3 S 
-l U D Zl(j 
1 2 , ’5 »/ 4 105, 
— a/a.) sin 6 cos 6- 
24 ' 945 45.1024 
2 ^ 
COS o 
1 *>• ft ft /26 83 2 ft 
+ ■■■■■ a., sm d cos o --cos 6 
2520 ' V 3 4 
