LIEUT. CLERK’S REPORT : ELEMENTS OF REDUCTION. 
357 
needle) on the sixteen principal points. The following- are the observations at King 
George’s Sound, the Mauritius, and the Cape of Good Hope. 
Ship’s head. 
King George’s 
Sound. 
Mauritius. 
Cape of 
Good Hope. 
Ship’s head. 
King George’s 
Sound. 
4 
Mauritius. 
Cape of 
Good Hope. 
N. 
1 
Oo 
Ox 
CRN 
— 0 05 
-0 25 
S. 
o / 
Not observed. 
o / 
+ 1 25 
o / 
-0 50 
N.N.W. 
— 1 15 
— 1 25 
Not observed. 
S.S.E. 
+ 2 40 
+ 1 15 
Not observed. 
N.W. 
— 2 05 
— 1 45 
— 0 05 
S.E. 
+ 3 25 
+ 1 10 
+ 1 55 
W.N.W. 
—3 20 
— 2 25 
-0 35 
E.S.E. 
+ 3 25 
+ 1 50 
+ 2 35 
W. 
—3 35 
— 3 05 
— 0 50 
E. 
+ 3 25 
+ 2 15 
+ 2 40 
W.S.W. 
—3 45 
— 3 05 
— 1 15 
E.N.E. 
+ 2 35 
+ 1 05 
+ 1 10 
s.w. 
— 1 55 
-1 35 
— 1 45 
N.E. 
+ 2 45 
+ 0 35 
4 0 45 
s.s.w. 
#3 00 
— 1 05 
— 0 35 
N.N.E. 
+ 2 20 
+ 0 25 
+ 0 05 
“ Allowing for the errors of observation, it appears from these observations that the 
iron is symmetrically distributed in reference to the compass placed on the same 
spot where the observations of inclination and intensity were made, and therefore 
that we may use the equations in Contributions V. and VI. 
“From these equations the values of a and b are found, — 
At King George’s Sound .... a — ’ 0296 ; ‘ b = '9867 ; 
Mauritius a — ' 02/2; & = - 9910 ; 
Cape of Good Hope a=- 0192 ; b='970G- 
“The values of a and b can be found independently of the compass, from the ob- 
servations of dip and intensity themselves, A' being supposed =1, by means of the 
formulae 
a sin 9— ~ 
9 
cos 9’ cos — cos 9 . cos 
(!•) 
and 
b cos 9= ^ cos 9' sin cos 
( 2 .) 
“ Values of <p' and 9' were obtained from observations on the sixteen principal points 
of the compass made at King George’s Sound, Mauritius, and the Cape of Good Hope. 
They are as follows : — 
Values of 9'. 
Observed Inclination. 
Observed Inclination. 
Ship’s head. 
King George’s 
Sound. 
Mauritius. 
Cape of 
Good Hope. 
Ship’s head. 
King George’s 
Sound. 
Mauritius. 
Cape of 
Good Hope. 
N. 
— 66 15 
— 54 38 
— 54 01 
S. 
-64 52 
o f 
— 53 46 
-53 28 
N.N.W. 
-66 33 
— 54 44 
— 54 35 
S.S.E. 
— 65 00 
— 53 41 
— 53 50 
N.W. 
-66 19 
-54 47 
— 54 56 
S.E. 
-65 29 
— 54 20 
— 53 51 
W.N.W. 
-66 07 
-55 02 
-54 47 
E.S.E. 
-65 52 
— 54 25 
-54 24 
w. 
-65 44 
— 55 21 
— 54 46 
E. 
— 66 23 
-54 50 
— 54 46 
w.s.w. 
-65 42 
-54 39 
— 54 31 
E.N.E. 
-66 07 
— 54 55 
-54 53 
s.w. 
-65 31 
— 54 29 
-53 45 
N.E. 
-66 17 
— 54 47 
-54 37 
s.s.w. 
-64 48 
-54 07 
— 53 09 
N.N.E. 
-66 31 
-54 27 
-54 25 
* This observation is not taken into account, being obviously erroneous. 
MDCCCXLVI. 3 A 
