Terrestrial Isomagyietic Lines. 285 
the values given in Table 1 obtained. The results are shown in the 
following table : — 
Table 3. 
Mean Station of District. 
aXc-aX. 
aYc-aY. 
I 
+ 27 
-32y 
-22y 
+ 27 
II 
-17 
+64 
+22 
—10 
Ill 
-27 
-50 
+39 
— 4 
IV 
+ 24 
+ 11 
-23 
+il 
V 
+30 
+20 
-24 
VI 
-69 
-35 
+40 
-16 
VII 
+69 
+55 
+ 3 
+ 8 
VIII 
- 7 
+ 2 
-30 
+ 2 
IX 
+16 
- 9 
-31 
+ 4 
X 
-91 
-55 
+ 56 
—23 
XII 
+ 17 
- 2 
-23 
+ 10 
XIII : 
- 9 
-27 
+ 4 
+ 17 
XIV 
+ 43 
+41 
- 7 
— 7 
XV 
+ 18 
+ 15 
- 4 
+ 8 
Finally, Table 4 gives the calculated values for the four intensities at 
the intersections of alternate whole degrees of latitude and of longitude. 
From these figures the respective terrestrial lines have been plotted as 
shown in maps 1, 2, 3, 4 (Plates VIII., IX., X., XL). 
Table 4. 
X. 
Zc. 
Xr. 
Y,. 
18°E. 
34°S. 
•30397 
•35428 
•16000 
•08749 
20 
34 
•31003 
•35865 
•15869 
•08578 • 
22 
34 
•31595 
•36285 
•15746 
•08391 
24 
34 
•32150 
•36689 
•15634 
•08189 
26 
34 
•32677 
•37074 
•15530 
•07971 
18 
32 
•29829 
•35122 
•16395 
•08674 
20 
32 
•30455 
•35574 
•16293 
•08502 
22 
32 
•31065 
•36010 
•16201 
•08315 
24 
32 
•31639 
•36429 
•16118 
•08111 
26 
32 
•32185 
•36831 
•16044 
•07891 
28 
32 
•3270.3 
•37216 
•15979 
•07659 
18 
30 
•29205 
•34808 
•16835 
•08577 
20 
30 
•29850 
•35276 
•16763 
•08404 
22 
30 
•30480 
•35727 
•16700 
•08215 
24 
30 
•31072 
•36161 
•16646 
•08012 
26 
30 
•31737 
•36579 
•16602 
■07792 
28 
30 
•32174 
•36980 
•16567 
•07557 
30 
30 
•32681 
•37364 
•16541 
•07307 
18 
28 
•28526 
•34486 
•17303 
•08457 
20 
28 
•29189 
•34969 
•17-260 
•08283 
22 
28 
•29838 
•35436 
•17226 
•08093 
24 
28 
•30450 
•35886 
•17202 
•07889 
