CHANGE IN DIRECTION OF EARTH’S MAGNETIC FIELD. 325 
Lat. 5° Oy S. PAITA, PERU. Long. 81° 05.5' W. 
Year. 
Magnetic 
dip or in¬ 
clination. 
Authority. 
Observer. 
Where recorded. 
1 R-2?. 
o 
+4.02 
J4.ll, Duperrey .... 
BecquerePs Trait6 du l^agnetisme, 1846. 
J3.93, Duperrey .... 
Phil. Trans. Royal Society, 1877. 
1832. 
+4.67 
"Rrmssins’fl.nlt_ 
Do. 
1836. 
+4.42 
“ La, Rnnit.fi ” . 
Do. 
1838. 
+4.53 
“ La, Vfinns ”. 
Do. 
1866. 
+4.97 
TTarlrnfiss 
Do. 
1893.9 .... 
+6.07 
Lieutenant Mottez, Fr. N... 
Annales Hydrographiques, vol. 1, 1893. 
Year. 
Observed. 
Computed. 
O-C. 
- 2 
0-0 . 
o 
0 
1823. 
+4.02 
+4.22 
—0.20 
0.0400 
1832 . 
+4.67 
+4.38 
+0.29 
0.0841 
1836 . 
+4.42 
+4.45 
—0.03 
0.0009 
1838. . 
+4.53 
+4.50 
+0.03 
0.0009 
■ Probable error of a single observation = ± 14'. 
1866. 
+4.97 
+5.14 
—0.17 
0.0289 
1893.9 .... 
+6.07 
+5.99 
+0.08 
0.0064 
0.1612 
Empirical equation for determining the inclination for any year: I = 4°.75-f- 
0.0231 (t — 1850) + 0.000119 (t — 1850) 2 . 
47—Bull. Phil. Soc., Wash., Vol. 13. 
