DIURNAL VARIATIONS OF TERRESTRIAL MAGNETISM. 
25 
Table D.—Comparison of the Potential Functions determined by Schuster and 
Fritsche from North and West Force Data, with those here determined from 
West Force Data alone. 
Annual terms. 
Seasonal terms. 
• 
Ampli- 
Present paper. 
Ampli- 
Present paper. 
tude. 
Schuster, 
Fritsche. 
tude. 
Schuster, 
Fritsche. 
— 
1870. 
— 
1870. 
Phase. 
1902. 
1905. 
Phase. 
1902. 
1905. 
C 2 X 
40 
58 
89 
59 
cp 
43 
47 
54 
59 
Xo 1 
35° 
24° 
24° 
30° 
«i x 
23° 
27° 
27° 
28° 
C 3 2 
5-8 
7-6 
9-2 
6-2 
C 3 1 
8-4 
11-5 
10-1 
6-2 
a -% 
35° 
27° 
31° 
25° 
K3 1 
344° 
337° 
311° 
347° 
cp 
0-41 
0-53 
0-63 
0-42 
Co 2 
6-0 
8-7 
11-2 
8-4 
«4 3 
47° 
40° 
67° 
35° 
ao 2 
63° 
63° 
75° 
62° 
Co 4 
0-0127 
0-0180 
0-0202 
_ 
Cf 
0-86 
0-69 
0-66 ' 
0-73 
«5 4 
62° 
55° 
78° 
— 
af 
25° 
30° 
- 18° 
6 ° 
C 3 3 
0-63 
0-72 
_ 
0-76 
«3 3 
91° 
104° 
— 
88 ° 
Cf 
0-030 
0-49 
_ 
0-33 
200 ° 
188° 
— 
173° 
The horizontal force harmonics in Table D show a considerable degree of agreement 
in regard to phase, especially for the main terms Q 2 X , Q 3 2 , Q, x , and Q 2 2 . The amplitudes 
obtained by Schuster generally exceed those of Fritsche and the present paper, 
including those for the maximum sunspot year 1905. The year 1870 was, however, 
one of abnormally great solar and magnetic activity. Detailed numerical agree¬ 
ment between the various sets of results is not to be looked for, owing to this and 
other reasons, and it is satisfactory that the different determinations yield values of 
amplitudes and phases which show such general agreement. 
The papers by Walker and van Bemmelen referred to in §§ 4, 5 contained the 
following results, which may be compared with the above :— 
Walker. Annual terms. C 2 X = 55 a 2 x = 25° 
C 3 2 = 4-3 a 2 — 23° 
van Bemmelen. „ ,, C 3 2 = 4’3 a 3 2 = 26° 
In Table E the coefficients A,/, obtained by Fritsche are compared with those 
of the present paper. The agreement for these vertical force results is much less good 
than for the horizontal force results in Table D. The reason for this is discussed in 
§ 3 (cf. also § 5). The other authors quoted have not analysed the vertical force 
VOL. CCXVIII.-A. 
E 
