— 237 — 
curve after the observations made from 1853—1864 at 
Trevandrum (British India), which station is situated only 
^ 24° more to the North than Sabang and not too much 
differing in longitude 4), 
Mean daily variation of D at Trevandrum 
for March, 1853—1864. 
Time. AD "Time. AAD 
Q^ 30" a 0.'053 Oh 30" p 0.114 
1 80 0. 046 1 30 0. 088 
2 30 0. 042 2 80 0. 273 
3 30 —0. 155 3 30 0. 371 
4 80 — 0. 292 4 30 0. 207 
5 30 —0. 345 5 30 —0. 004 
6 30 — 0. 420 6 30 0. 025 
7 80 — 0. 356 7 30 0. 007 
8 30 — 0. 146 8 30 —0. 024 
9 30 0. 114 9 30 —0. 051 
10 30 0. 312 10 30 —0. 058 
11 30 0. 946 11 30 0. 041 
From these values it is easy to deduce half-hourly values, 
which we can compare with those observed at Sabang. 
Saban. Trevandrum. Saban. Trevandr um. 
9" 30% 0.'0 f ge 5 0.09 
10:0 0.3 0. 23 1l 90^ 04 0. 09 
10 30 0. 0 0. 31 2 0 0.8 017 
IE 0 —0,2 0. 25 2 30 —0.3 0. 27 
11 30 . —0.1 0. 19 3 0 01 0. 34 
120" 0.3 0. 11 3 390 3 —0.1 0. 37 
12 30 —0.7 0. 09 4.0 —0.1 0. 32 
Mean —0. 24 0.22 
If we apply the difference of the average readings, —0.'24 
and 0.'22, ie. 0'.46 to the Sabang values, the latter may be 
considered to be converted into departures from the daily mean. 
1) Trevandrum magnetical Observations. Vol. I (1874), p. 107. 
