SURVEY OP THE BRITISH ISLES FOR THE EPOCH JANUARY I, 1891. 
13 
Comparisons of Magnetometer 61 with the Kew Standard Instrument. 
S 
K 
Date. 
Observer. 
(Survey 
(Kew 
K—S=/I. 
II 
1 
M 
S-K'. 
Instrument). 
Instj’ument). 
June 13,1890 . . 
B. 
1°7 51-8 
17 51-8 
d-0 
17 52-2 
-()-4 
„ 14, „ . . • 
B. 
17 51-4 
17 51-4 
0-0 
17 51-8 
-0-4 
„ 17, „ . . . 
B. 
17 52 4 
17 61-4 
-10 
17 51-8 
+ 0-6 
17, „ . . . 
B. 
17 53-2 
17 52'-4 
-0-8 
17 52-8 
+ 0-4 
„ 18, „ . . . 
B. 
17 51-7 
17 51-6 
-0-1 
17 52-0 
-0-3 
„ 18, ,, . . . 
B. 
17 51-9 
17 51'4 
-0-5 
17 51-8 
+ 0-1 
II 
1 
o 
Mean . 
= ±0-37 
Nov. 24, 1891. . . 
Gr. 
17 44-0 
17 44-8 
-bO-8 
17 44-1 
-OT 
„ 24, „ . . . 
G. 
17 44-8 
17 44-8 
00 
17 44T 
+ 0-7 
„ 24, ,, . . . 
G. 
17 43-4 
17 43-9 
+ 0-5 
17 43-2 
+ 0-2 
„ 24, „ . . . 
G. 
17 42-8 
17 43-6 
+ 0-8 
17 42-9 
-OT 
„ 24, „ . . . 
G. 
17 42-3 
17 43T 
+ 0-8 
17 42-4 
-OT 
„ 24, „ . . . 
G. 
17 42-4 
17 43-8 
+ 1-4 
17 43T 
-0-7 
/l=+0-7 
Mean . 
= ±0-32 
Oct. 20,* 1892 . . 
G. 
17 40-6 
17 37 1 
-3-5 
17 38-0 
-|-2'6 
„ 20, „ . . 
G. 
17 42-5 
17 40-7 
-1-8 
17 41-6 
+ 0-9 
„ 21, „ . . 
G. 
17 37-2 
17 .38-7 
+ 1-5 
17 39-6 
-2-4 
„ 21, „ . . 
G. 
17 41-8 
17 41-7 
-OT 
17 42-6 
-0-8 
o 
1 
II 
Mean . . 
= ±1-67 
* The curves given by the self-registering instruments indicated some distin’bance. 
