SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY I, 1891. 
15 
Comparisons of Magnetometer 73 with the Kew Standard Instrument. 
Date. 
Observer. 
S 
(Survey 
Instrument.) 
K 
(Kew 
Instrument.) 
K-S = /3. 
K-/3=K'. 
S-K'. 
March 23, 1892 . . 
G. 
17 4.3-4 
17 42-1 
-1-3 
17 43-2 
+ 6-2 
,, 23, ,, 
G. 
17 47-3 
17 46-1 
-1-2 
17 47-2 
+ 0-1 
23, ,, 
G. 
17 47-8 
17 47-1 
-0-7 
17 48-2 
-0-4 
,, 23, ,, 
G. 
17 44-9 
17 4.3-3 
-1-6 
17 44-4 
1 r\,h 
-r VO 
„ 24, „ . . 
G. 
17 42-2 
17 41-6 
-0-6 
17 42-7 
-0-5 
24, „ 
G. 
17 44-8 
17 44-1 
-0-7 
17 45-2 
-0-4 
„ 24, „ . . 
G. 
17 45-2 
17 44-9 
-0-3 
17 46-0 
-0-8 
„ 25, „ . . 
G. 
17 46-2 
17 44-2 
-2-0 
17 45-3 
+ 0-9 
„ 25, „ . . 
G. 
17 47-5 
17 46-1 
-1-4 
17 47-2 
+ 0-3 
tlrr-1-1 
Mean , 
= ±0-46 
Oct. 11, 1892 . . . 
W. 
17 40-5 
17 37-9 
-2-6 
17 40-0 
+ 0-5 
W. 
17 46-2 
17 45-1 
-1-1 
17 47-2 
-1-0 
„ 11, „ . . . 
W. 
17 42-1 
17 40-4 
-1-7 
17 42-5 
-0-4 
„ 13, „ . . . 
W. 
17 41-9 
17 40-0 
-1-9 
17 4-2-1 
-0-2 
13 
i) n * • • 
W. 
17 43-8 
17 41-8 
-2-0 
17 43-9 
-0-1 
„ 13, „ . . . 
W. 
17 43-9 
17 40-8 
-3-1 
17 42 9 
+ 1-0 
1 
II 
'srr 
Mean . 
= ±0-53 
Collecting the mean results into one table and subtracting from each 2'’5, so as to 
find the correction necessary to bring the readings of each instrument into accord 
with the survey standard above defined, we get the following results 
