CHANGE IN DIRECTION OF EARTH S MAGNETIC FIELD. 
307 
Lat. 13° 05' N. BARBADOS (BRIDGETOWN). Long. 59° 37' W. 
Year. 
Magnetic 
dip or in¬ 
clination. 
Authority. 
Observer. 
Where recorded. 
1722.7 .... 
o 
44. 5 
Appendix No. 1, Report of United States Coast 
and Geodetic Survey for 1895, p. 266. 
Do. 
1835.3 .... 
43.76 
vTTome.. 
1836.. 
43.48 
1846. 
43.95 
Sohomhnrerlc. 
Do. 
1880. 
43.37 
H. M. S. Challenger Mag¬ 
netic Chart. 
Report of Scientific Results of the Exploring 
Voyage of H. M. S. Challenger, 1873-1876, 
Physics and Chemistry, vol. II. 
1890.3 .... 
43.13 
E. D. Preston, assistant, 
United States Coast and 
Geodetic Survey. 
Bulletin No. 23, United States Coast and Geodetic 
Survey, March, 1891. 
Year. 
Observed. 
Computed. 
O-C. 
-2 
O-C . 
1722.7 .... 
o 
44. 5 
o 
44.49 
+0.01 
.0001 
i 
1835.7 .... 
43.62 
43.82 
—0.20 
.0400 
| 
1846.. 
43.95 
43.70 
+0.25 
.0625 
Probable error of a single observation = ± 8'. 
1880. 
43.37 
43.34 
+0.03 
.0009 
1890.5 .... 
43.13 
43.23 
—0.10 
.0100 
.1135 
Empirical equation for determining the inclination for any year : iS-f 43°.66 
— 0.0108 {t — 1850) — 0.000034 (t — 1850) 2 . 
