12 
LIEUT.-COLONEL SABINE ON TERRESTRIAL MAGNETISM. 
flector, which occurred between the forenoon and afternoon observations of the 12th 
of February, was equivalent to nearly a degree in the angle v', and is obvious on a 
simple inspection of the table of observations. In this case, therefore, we require to 
form two tables of the values of w ' ; the one, Table A, corresponding to the force of 
the deflector between August 1839 and February 12th, 1840, and the other, Table B, 
to the weaker force between February ] 2th and the Cape of Good Hope. 
" 
Values of w', Deflector S. 
(A.) August 1839 to February 12, 1840. 
(B.) February 12 to March 25, 1840. 
o S rs - 
o g rs - 
o grs- 
30 = 2-754 
37 = 2-410 
35 = 2-291 
31 — 2-704 
38 = 2-359 
36 = 2-260 
32 = 2-655 
39 = 2-310 
37 = 2-235 
33 = 2-606 
40 - 2-260 
38 = 2-210 
34 = 2-556 
41 = 2-210 
39 = 2-186 
35 == 2-508 
42 = 2-160 
40 - 2-161 
36 = 2-459 
43 = 2-110 
41 = 2-135 
| 
42 = 2-110 
For the first series we have London as the primary station, where I = 1, v = 30° 19', 
and w =2*737 ; whence 
I' = *1845 w' cosec v'. 
the values of w' being taken from Table A. And for the second series we have the 
Cape as the primary station, where v = 35° 40', w = 2*270, and I, derived from the 
experiments with the constant weights = 0*713 (London = 1) ; consequently at 
other stations 
r = *1837 w' cosec v'. 
the values of w' being taken from Table B. 
The loss of force sustained by deflector S. causes a similar interruption in the con- 
tinuity of the line connecting the terminations of the ordinates derived from the 
observations in which the deflectors N. and S. were used conjointly ; we have therefore 
in this case also two tables of the values of w', one for the first, and the other for 
the second series. 
Values of w', Deflectors N. and S. 
(A.) August 1839 to February 12, 1840. 
(B.) February 12 to March 25, 1840. 
o grs- 
O grs- 
O grs. 
44 - 3-784 
53 - 3-118 
51 = 3-037 
45 = 3-674 
54 = 3-056 
52 = 2-989 
46 = 3-584 
55 = 2-995 
53 = 2-943 
47 — 3-505 
56 = 2-936 
54 = 2-896 
48 = 3-430 
57 = 2-880 
55 = 2-853 
49 = 3-366 
58 = 2-828 
56 = 2-813 
50 = 3-304 
59 = 2-780 
57 = 2-775 
51 = 3-242 
52 = 3-180 
60 = 2-738 
58 = 2-740 
