314 CAPTAIN ELLIOT’S MAGNETIC SURVEY OF THE INDIAN ARCHIPELAGO. 
The following observations were taken at the Cocos : — 
Date. 
Stars and Moon. 
Mean difference 
between Greenwich 
and Cocos, 
# and C . 
Resulting 
Longitude East. 
Sept. 6 
8 
9 
10 
12 
13 
fl Ophiuchi, C I, Sagittarii, X Sagittarii 
0 and Sagittarii, (J I, a 2 Capricorni 
a 2 Capricorni, (I I, £ and ju. Aquarii 
£ and fx. Aquarii, ([ I, y and 5 Capricorni 
([ I, p and s Piscium 
s Piscium, ([ II 
m s 
14 09-86 
14 49*08 
15 00-13 
15 11-14 
15 20*05 
15 27-42 
15 44-21 
15 59*04 
ongitude 
h m s 
6 27 18 
6 28 36 
6 26 31 
6 27 48 
6 27 05 
6 26 45 
6 28 23 
6 27 43 
6 27 22 
14 
15 
([ II., fx and 0 Piscium 
0 Piscium, ^ II., ?, s and jix Ceti 
Mean L 
The mean longitude resulting from nine sets of lunar distances, was 6^* 26“ 47® : 
but these were not to be trusted, as the sum of the distance and the true altitudes of 
the ©and (I at each observation amounted to 180°, very nearly. I consider it my 
duty, however unsatisfactory may be the observations, to publish one set in detail, 
as their value, small or large, may thus be inferred ; although but little could be ex- 
pected from a small altitude and azimuth on an ordinary table stand, as a substitute 
for a transit instrument, it was better to depend upon these observations than upon 
the chronometer, which had been long in use, and which yielded such rates, on suc- 
cessive days at the Cocos, as the following : — 
-fr7, +9®-l, +1P-4, -f8®-8, +7^-8, -1-6*7, +6®7, +B*-4, -l-8*-9, 
-1-8*7, -f8*'9, +9*-l, -l-9*‘5, -l-12*-2, -l-10*-4, -l-9*-9, -h8*-6, H-8*-9; 
the mean rate being -1-8®‘19; of course no dependence could be placed upon such 
rates as these for the longitude. 
Dip or Inclination of the Needle. 
The Dip Observations are contained in Table F., from page cxxx to cxxxix in- 
clusive. 
On commencing the Survey in 1846 I was not furnished with a dip circle ; a Fox’s 
dip circle had been stolen from the observatory at the latter end of 1845, and three 
dip circles had been sent, in 1844, to England to Mr. Barrow, but they had not 
then reached Singapore, having been detained at Bombay through some mistake. 
In March 1846 I received a dip circle with four needles from Mr. Taylor, the then 
astronomer at Madras: the needles were very inferior; one of them, A 1 L, having 
a difference of 24° reading on the reversal of the poles : the observations with this 
needle should perhaps have been omitted. The correction to be applied to A 1 L was 
28', with only half the value assigned to it, which has been given to each of the other 
needles, and each recorded observation with the Madras circle is the mean of forty- 
eight readings. With the Madras dip circle I took observations at Singapore, in 
