16 
MR. A. W. RtiCKER AND DR. T. E. THORPE ON A MAGNETIC 
Date. 
1 
Survey Instrument. 
No. of 
Observations. 
Observers. 
No. 60. 
No. 61. 
O 
p 
No. 73. 
July 17-18, 1884 . . . 
- O'l 
/ 
4 
2 
R. and T. 
April 2, 1886 .... 
- 0-2 
•• 
1 
T. 
Sept, and Oct., 1887 . 
- 0-3 
6 
R. 
91 11 11 • • 
b-0 
• • 
6 
T. 
1 
i June 3-6, 1890 . 
- 2-2 
7 
G. 
„ 13-18, „ . . . 
- 2-9 
6 
B. 
April 16-24, 1891 . . 
- 6T 
12 
W. 
Oct. 12-14, „ . . 
, , 
- 5-1 
4 
W. 
Nov. 12-18, ,, 
- 1-9 
, , 
, , 
7 
G. 
„ 24, „ . . 
- 1-8 
6 
G. 
*Dec. 4, ,, . . 
- 2-3 
6 
G. 
March 23-25, 1892 . 
- 3-6 
9 
G. 
April 21-22, „ . . 
- 4-7 
10 
W. 
Oct. 7-10, „ . . 
, , 
— 57 
, , 
6 
W. 
„ 11-13, „ . . 
, , 
- 4-6 
6 
W. 
20-21, „ . . 
- 3-4 
4 
G. 
24-25, „ . . 
- 2-0 
4 
G. 
Upon this Table vve base the following Table of Corrections, which were those 
actually used in the reductions. 
Year. 
Coil 
cctions ajjplied to Magnetometers. 
60 
61 
70 
73 
1884 to 88 . . 
- b 
b 
1889 .... 
-1-0 
-1-0 
1890 .... 
-2-0 
-20 
— 5*5 
1891 .... 
-2'0 
-2 0 
— 5'5 
1892 .... 
-20 
— 4'6 
-5-2 
-4T 
'ihe inagTiitude of the corrections which thus had to be applied to instruments all 
of which rank as “absolute” may cause surprise. 
* As there were only check observations on the more complete set taken in November, details 
not given on p. 12. 
are 
