CAPTAIN ELLIOT’S MAGNETIC SURVEY OF THE INDIAN ARCHIPELAGO. 311 
tinged of a dark purple colour, although not absolutely black. This instrument was 
placed on a table outside the tents and freely exposed to the sun. After the instru- 
ments in the tent were observed, the solar radiation thermometer was read off hourly, 
from 7 a.m. to 4 or 3 p.m., and the maximum of the day recorded, with the time at 
which it was observed, being generally 1 1 a.m., noon, or 1 p.m. 
The minimum self-registering thermometer was placed on a table outside the tent 
at night, and the minimum temperature shown by the index read off at 7 a.m. 
The subjoined Table contains the maximum solar radiation, and the mean at each 
station; the minimum and the mean of the self-registering thermometer exposed 
at night ; and lastly, the mean of the standard thermometer, by dividing by the num- 
ber of observations, and likewise by Dr. Lloyd’s method of equal intervals, each 
result being the mean of three sets, at 3, 4, 5 a.m. ; 1 1 a.m., noon, 1 p.m. ; and 8, 9, 
10 P.M. 
station. 
Latitude. 
Longitude. 
Mean date 
corresponding 
to the 
1 No. of days. | 
1 No. of hours. 1 
Solar Radiation. 
Terr. Radiation. 
Standard Thermometer. 
Maxi- 
mum. 
Mean. 
Mini- 
mum. 
Mean. 
Mean by 
equal in- 
tervals. 
Mean of 
the 
whole set. 
Diff. 
16 29 46 N. 
o / // 
Moulmein 
97 45 30 E. 
Middle of April. 
7 
19 
111-5 
110-0 
70-2 
71-9 
86-0 
88-4 
+2-0 
Madras 
13 04 09 
80 16 00 
Beginning of Sept. 
34 
19 
1150 
104-7 
74-0 
76-6 
84-3 
85-2 
+ 0-9 
Nicobar 
9 10 12 
92 48 23 
Beginning of Feb. 
5 
19 
1020 
98-9 
67-7 
68-4 
79-9 
80-9 
+ 1-0 
Sambooanga 
6 54 20 
122 13 45 
End of May. 
6 
19 
104-7 
102-6 
71-4 
723 
80-7 
82-5 
+ 1-8 
Pulo Peenang 
5 25 30 
100 24 38 
End of January. 
5 
19 
105-8 
103-0 
70-8 
71-9 
81-3 
81-7 
+0-4 
Pulo Dinding 
4 12 48 
100 32 52 
End of January. 
3 
19 
113-8 
110-9 
70-6 
72-2 
82-4 
82-6 
+0-2 
1 33 54 
110 29 00 
Middle of June. 
26 
24 
79-8 
79-6 
-0-2 
Middle of July. 
27 
24 
68-6 
71-8 
79-0 
78-8 
-0-2 
Middle of August. 
19 
24 
69-3 
71-6 
78-8 
78-7 
-0-1 
Keemah 
1 21 55 
125 07 59 
End of June. 
10 
19 
112-2 
108-6 
68-3 
70-3 
80-9 
81-5 
+0-6 
Pulo Peesang 
1 27 53 
103 19 15 
Middle of January. 
5 
18 
81-3 
81-5 
+0-2 
Singapore 
1 18 32 
103 56 30 
Beginning of Dec. 
30 
19 
107-7 
98-3 
67-6 
71-1 
79-8 
79-8 
00 
0 58 58 S. 
100 31 15 
End of October. 
13 
19 
69-4 
70-6 
79-2 
80-5 
+ 1-3 
Middle of November. 
26 
19 
69-8 
71-1 
79-7 
80-8 
+ 1-1 
Middle of December. 
26 
19 
68-5 
70-8 
80-3 
81-3 
+ 1-0 
Beginning of Jan. 
13 
19 
80-5 
81-7 
+ 1-2 
3 53 54 
102 28 45 
Beginning of Sept. 
5 
19 
69-8 
71-2 
78-4 
79-3 
+0-9 
6 09 52 
106 58 00 
Middle of November. 
19 
24 
69-2 
72-4 
80-5 
80-3 
-0-2 
Middle of December. 
26 
24 
69-8 
72-6 
80-3 
79-8 
-0-5 
Middle of January. 
25 
24 
68-5 
71-1 
80-0 
80-1 
+0-1 
Middle of February. 
24 
24 
70-7 
72-6 
79-6 
79-6 
0-0 
Middle of March. 
27 
19 
69-2 
72-9 
80-9 
81-3 
+0-4 
Middle of April. 
26 
19 
69-2 
715 
80-8 
81 3 
+0-5 
Middle of May. 
26 
19 
67-4 
69-9 
80-7 
81-2 
+0-5 
Middle of June. 
26 
19 
80-5 
81-0 
-j-0*5 
Cocos or Keebngs 
12 05 38 
96 50 30 
Middle of September. 
27 
19 
105-5 
99-5 
72-2 
74-9 
79-2 
79-2 
0-0 
Survey, and Instruments employed. 
The observations connected with the Survey relate to absolute determination, such 
as latitude, longitude, dip, horizontal intensity, and variation or magnetic declina- 
tion, and this is the order in which the subject will be treated ; but previously, it 
may be as well to state in a few words, how the Survey on land was conducted. On 
my arrival at a station I had my small tent pitched, for the reception of the magnetic 
instruments ; this was generally put up the evening of my arrival ; and the next 
morning at daybreak I commenced observing. The instruments in use were a 6-inch 
dip circle, a portable declinometer for magnetic declination and intensity, an altitude 
