r 
LIEUT. -COLONEL SABINE ON TERRESTRIAL MAGNETISM. 29 
§ 4. New Determination of the Magnetic Elements at Otaheite. 
In M. Gauss’s “General Theory of Terrestrial Magnetism*,” there is a note to 
the following effect : — “ Otaheite is a station of the highest importance for the future 
improvement of the magnetic elements : the difference between the two determina- 
tions of intensity made there by different observers, viz. Erman IT 72 in 1830, and 
FitzRoy T017 in 1835, is much greater than can with any degree of probability be 
attributed to yearly changes, and considerably exceeds the greatest difference between 
the computed and observed intensities at the eighty-six stations at which the theory 
has been compared with observations.” 
The importance which M. Gauss attached to a more exact determination of the 
magnetic elements at Otaheite was communicated to Captain Belcher in a letter 
from Captain Beaufort, which also conveyed to him permission from the Admiralty 
to touch at that Island on his homeward voyage. Quitting Bow Island in March 
1840, Captain Belcher arrived at Otaheite in April, and made there the obser- 
vations contained in Tables XI. and XIII., of which the results are given in Tables 
XII. and XIV. 
Table XI. — Observations with the Intensity Needles at Otaheite. 
1840. 
Needle. 
Time. 
Therm. 
Corrected 
1840. 
Needle. 
Time. 
Therm. 
Corrected 
Time. 
Time. 
April 
4 
5 
s 
483-9 
O 
87 
May 6 
8 
478-9 
8°8l 
476-3 
April 
4 
5 
483-7 
87 
May 6 
8 
479-1 
86 1 
April 
4 
5 
484-2 
88 
May 7 
8 
479-6 
77/ 
May 
3 
5 
482-8 
90 
May 7 
8 
478-6 
76) 
May 
3 
5 
482-1 
90 
s 
May 6 
9 
443-3 
851 
May 
4 
5 
480-8 
74 
> 
479-5 
May 6 
9 
443-4 
84 > 
441-6 
May 
4 
5 
482-3 
86 
May 7 
9 
444-2 
75j 
May 
4 
5 
482-2 
88 
May 6 
11 
480-6 
72 1 
May 
4 
5 
482-2 
89 
May 6 
11 
480-4 
so y 
478-0 
May 
5 
5 
481-6 
76 
May 6 
11 
480-7 
89 J 
May 
6 
5 
481-3 
73j 
May 6 
12 
408-8 
721 
April 17 
5 
480-1 
77 
478-2f 
May 6 
12 
409-1 
85 y 
406-8 
April 17 
5 
480-6 
771 
May 6 
12 
409-2 
88J_J 
May 
6 
7 
547-9 
941 
May 6 
13 
399-8 
731 
May 
6 
7 
547-9 
94 
544-2 
May 6 
13 
400-7 
86 y 
398-2 
May 
6 
7 
548-4 
77 J 
May 6 
13 
400-6 
86 J 
* Resultate fiir 1838, I. 
f Observed at Papeite : the other observations with No. 5, as well as all the observations with other needles, 
were made at Point Venus. 
