Secular Variation of the Magnetic Eleme?its. 
189 
Date. 
1908-51 
1903-83 
Ging-inMoon. (2, 3) 
Declination, Dip. Horizontal Intensity, 
21° 58'-9 W. 6P 27'-6 S. -17830 
23 03-2 61 05-3 -18231 
Secular Variation. 
1908-51-1903-83 = 4-68 yrs. - 13'-7 +4'-8 
-85y 
Date. 
1913-52 
1903-74 
Greyling-stad. (2, 7) 
Declination. Dip. Horizontal Intensity, 
20° 18'-6 W. 59° 55'-l S. -18100 
22 22-1 58 58-4 -18954 
Secular Variation. 
1913-52-1903-74 = 9-78 yrs. - 12'-6 + 5'-8 
-87y 
1910 
1905 
1903 
1899 
Declination, 
2° 41'-5 W. 
3 12-7 
3 21-4 
3 50-6 
Helwan. (9) 
Dip. 
40° 40'-5 N. 
40 36-2 
40 31-2 
1898-9 40 31-9 
Horizontal Intensity. 
-30029) 
-30159) ■ 
-30209 T.M. xii. p, 
1899 -30145 
213 
180 
Dip reached a minimum in 1901, 
H.I. reached a maximum in 1902. 
Date, 
1910-1905 = 
1905-1899= 
5 yrs. 
: 6 yrs . 
Secular Variation. 
Declination. 
-6'-2 W. 
-6-3 
Dip. 
+ 0'-9 
+ 0-9 
Horizontal Intensity. 
-26y 
-2y 
Date. 
1908-94 
1907-08 
Hollerivier. (3, 6) 
Declination. Dip, Horizontal Intensity, 
26° 58'-9 W. 59° 23'-7 S. -17955 
27 14-6 59 08-9 -18158 
Secular Variation. 
1908-94-1907-08 = 1-86 yrs. - 8'-5 +7'-9 
-109y 
