CHANGE IN DIRECTION OF EARTH’S MAGNETIC FIELD. 299 
Lat. 31° ]5' N. 
SHANGHAI. 
Long. 121° 29' E. 
Year. 
Magnetic 
declina¬ 
tion. 
Observer. 
1858. 
o 
-f 1.83 
Novara, Expedition. 
1875. 
+1.98 
1876. 
+2.02 
1877. 
+2.02 
1878. 
+2.00 
1879. 
+2.02 
1880. 
+2.03 
^Jesuit missionaries. 
1881. 
+2.05 
1882. 
+2.09 
1883. 
+2.08 
1884. 
+2.13 
Year. 
Observed. 
Computed. 
O-C. 
2 
o-c. 
o 
o 
1858. 
1.83 
1.92 
—0.09 
0.0081 
1875. 
1.98 
2.00 
—0.02 
0.0004 
1876. 
2.02 
2.01 
+0.01 
0.0001 
1877. 
2.02 
2.02 
0.00 
0.0000 
1878. 
2.00 
2.02 
—0.02 
0.0004 
1879. 
2.02 
2.03 
—0.01 
0.0001 
1880.. 
2.03 
2.04 
—0.01 
0.0001 
1881. 
2.05 
2.05 
0.00 
0.0000 
1882. 
2.09 
2.06 
+0.03 
0.0009 
1883. 
2.08 
2.07 
+0.01 
0.0001 
1884. 
2.13 
2.08 
+0.05 
0.0025 
0.0127 
Authority. 
Where recorded. 
Phil. Trans. Royal Society, 1875. 
The Meteorological Elements of the Climate of 
Shanghai, Zi-Ka-Wei Observatory. 
Probable error of a single observation = ± 1.62'. 
Empirical equation for determining the declination for any year: v = 1°.9084 
- 0.000012 {t — 1850) + 0.000149 (t — 1850) 2 . 
