CHANGE IN DIRECTION OF EARTH’S MAGNETIC FIELD. 279 
Lat. 6° 08 / S. 
BATAVIA, JAVA. 
Long. 106° 48' E. 
Year. 
Magnetic 
declina¬ 
tion. 
Authority. 
Observer. 
Where recorded. 
1605. 
1609. 
1767.. ... 
1814. 
1828. 
1846. 
1858. 
1876.5.. 
1882.75 
1883.5.. 
1884 . 
1885 . 
+3.33 
+3.00 
+1.42 
—0.28 
—0.52 
— 0.88 
—1.08 
—1.70 
—1.93 
—1.93 
—1.91 
—1.89 
Saris 
Wallis. 
B. Hall. 
Blosseville...... 
Elliot. 
Novara Expedition, 
van Rijckevorsel.... 
van Stock. 
Hansteen’s Magnetismus der Erde, Christiana, 
1819. 
Do. 
Becquerel’s Trait 6 du Magnetisme. 
Phil. Trans. Royal Society, Part II, 1877. 
Do. 
Do. 
Published by Royal Academy of Sciences, Am¬ 
sterdam. 
Magnetical and meteorological observations at 
the Batavian Observatory, Vols. VI and VII. 
Year. 
Observed. 
Computed. 
O-C. 
c+c 2 . 
o 
o 
1605. 
+3.33 
+2.94 
+0.39 
0.1521 
1 
1609. 
+3.00 
+3.12 
— 0.12 
0.0144 
1767. 
+1.42 
+1.87 
—0.45 
0.2025 
1814. 
—0.28 
—0.34 
+0.06 
0.0036 
1828.. 
—0.52 
— 0.86 
+0.34 
0.1156 
1846. 
— 0.88 
—1.35 
+0.47 
0.2209 
Probable error of a single observation = ± 15 '. 
1858. 
—1.08 
—1.56 
+0.48 
0.2304 
Period — 400 years. 
1876.5 .... 
—1.70 
—1.67 
—0.0.3 
0.0009 
1882.75 ... 
—1.93 
—1.64 
—0.29 
0.0841 
1883.5 .... 
—1.93 
—1.64 
—0.29 
0.0841 
1884........ 
—1.91 
—1.63 
—0.28 
0.0784 
% 
1885. 
—1.89 
—1.63 
—0.26 
0.0676 
1.2546 
Empirical equation for finding the declination for any year: v = 1°.494 
sin 0.9 {t — 1850) — 2.928 cos 0.9 (t — 1850). 
1.194 
