276 
LITTLEHALES. 
Lat. 18° 28' S. ARICA, PERU. Long. 70° 20*' W. 
Year. 
Magnetic 
declina¬ 
tion. 
Authority. 
Observer. 
Where recorded. 
171 a 
0 
— 8.00 
"Rvfiwsf.p.v’s Trp.n.tisA r>n Mn.p- TT.rHnVv 1884 
1821. 
—10.42 
B. Hall. 
—--- ~ ~ ~--- --0*7 --"7 
Becquerel’s Trait 6 du Magnetisme. 
1 
1827. 
—10.75 
1835 
— 11.00 
[Sabine’s Collection, Phil. Trans. Royal Society, 
| 1877. 
1858 
— 10.88 
| 
1883. 
— 10.00 
Ensign Favereau, 
Fr. N. 
Annales Hydrographiques, 2 d series, 1884. 
1893. 
— 9.87 
Lieut. Mottez, Fr. N. 
Annales Hydrographiques, 2 d vol., 1893. 
Year. 
Observed. 
Computed. 
O-C. 
- 2 
O-C. 
1713. 
0 
— 8.00 
0 
— 8.026 
+0.03 
0.0009 
1 
i 
1821. 
—10.42 
—10.581 
+0.16 
0.0256 
1 
1827. 
—10.75 
—10.692 
—0.06 
0.0036 
I 
| 
I Probable error of single observation — + 06'. 
1835. 
— 11.00 
—10.793 
— 0.21 
0.0441 
1 
1 
1 
t Period = 240 years. 
1858. 
— 10.88 
—10.738 
—0.14 
0.0196 
1883. 
— 10.00 
—10.072 
+0.07 
0.0049 
1893. 
— 9.87 
— 9.808 
—0.06 
0.0036 
0.1023 
Empirical equation for finding the declination for any year: v — — 9°.4 -f 0.223 
sin 1.5 (< — 1850) — 14.61 cos 1.5 (<—1850). 
