BRITISH ISLES FOR THE EPOCH JANUARY 1, 1915. 
53 
Table YII. (continued). 
District IX. 
Station. 
Survey, January 1, 1915. 
Survey, January 1, 1886. 
Differences. 
H. 
D. 
I. 
H. 
D. 
I. 
H. 
D. 
I. 
y 
O 4 
o / 
y 
o / 
o / 
y 
Southampton . . . 
18,696 
15 19-2 
66 35-5 
— 
— 
— 
— 
— 
Alresford .... 
18,686 
15 17-6 
66 40-8 
18,241 
18 9-7 
67 22-3 
+ 445 
-2 52-1 
-0 41-5 
Brecon. 
18,116 
16 42-8 
67 33-4 
17,701 
19 38-6 
68 15-8 
+ 415 
-2 55-8 
-0 42-4 
Bude. 
18,513 
17 1-5 
67 0-2 
18,080 
19 56-5 
67 44-2 
+ 433 
-2 55-0 
-0 44-0 
Cardiflf. 
18,396 
16 27-7 
67 10-0 
17,944 
19 19-7 
67 52-3 
+ 452 
-2 52-0 
-0 42-3 
Clifton. 
18,419 
16 16-3 
67 11-3 
17,996 
19 10-7 
67 48-7 
+ 423 
-2 54-4 
-0 37-4 
Clovelly. 
18,451 
16 55-6 
67 6-7 
18,000 
19 53-8 
67 49-9 
+ 451 
-2 58-2 
-0 43-2 
Falmouth .... 
18,814 
17 2-6 
66 25-3 
18,323 
19 53-4 
67 15-0 
+ 491 
-2 50-8 
-0 49-7 
Gloucester .... 
18,200 
16 16-5 
67 25-1 
17,811 
19 12-9 
68 4-3 
+ 389 
-2 56-4 
-0 39-2 
Ilfracombe .... 
18,394 
16 53-8 
67 9-8 
17,952 
19 46-5 
67 53-8 
+ 442 
-2 52-7 
-0 44-0 
King’s Sutton . . 
18,196 
15 57-4 
67 25-2 
17,778 
18 51-8 
68 6-4 
+ 418 
-2 54-4 
-0 41-2 
Milford. 
18,228 
17 11-4 
67 28-6 
17,808 
20 8-8 
68 9-9 
+ 420 
-2 57-4 
-0 41-3 
Oxford. 
18,257 
15 38-6 
67 17-8 
17,890 
18 33-7 
67 57-5 
+ 367 
- 2 55-] 
-0 39-7 
Plymouth .... 
18,789 
16 36-2 
66 25-4 
18,309 
19 31-6 
67 14-7 
+ 480 
- 2 55•4 
-0 49-3 
Ryde. 
18,802 
15 9-7 
66 24-4 
18,391 
18 1-6 
67 7-8 
+ 411 
-2 50-9 
-0 43-4 
St. Gyres. 
18,657 
16 37-1 
66 41-9 
18,260 
19 28-6 
67 26-2 
+ 397 
-2 51-5 
-0 44-3 
Salisbury .... 
18,607 
15 32-0 . 
66 44-2 
18,242 
18 23-9 
67 25-6 
+ 365 
-2 51-9 
-0 41-4 
Swansea ... 
18,328 
16 50-6 
67 19-4 
17,931 
19 45-6 
67 59-7 
+ 397 
-2 55-0 
-0 40-3 
Swindon. 
18,378 
15 23-8 
67 9-6 
17,930 
— 
67 51-4 
+ 448 
— 
-0 41-8 
Taunton . 
18,575 
16 16-4 
66 49-2 
18,154 
19 10-7 
67 32-7 
+ 421 
-2 54-3 
-0 43-5 
Wallingford.... 
18,418 
15 28-2 
67 5-2 
17,986 
18 21-6 
67 48-4 
+ 432 
-2 53-4 
-0 43-2 
Weymchith .... 
18,807 
15 52-7 
66 26-2 
18,329 
18 46-7 
67 11-7 
+ 478 
-2 54-0 
- 0 45 • 5 
Mean . 
+ 427 
-2 54-0 
-0 42-8 
Portree is abnormal in the other direction, for the increase of H is 592y and the 
decrease in I 65'. Coleraine has an increase of 1053y in H and a decrease in I of 39' 
(practically normal), while Cookstown Junction in the same district has an increase 
of only 96y in H and a decrease of 4' in I. With these exceptions nothing very 
remarkable is apparent until we come to analyse the disturbing forces. 
We conclude that “ as a whole the change ot the magnetic elements in 29 years 
has been remarkably uniform at all points in the British Isles.” 
The mean annual change of the elements during the 29 years is set out for the 
different districts in Table VIII. They appear to have a systematic although small 
dependence on the latitude and longitude. 
In all cases the agreement between the deduced formulae and the observations is 
good, except in the case of the vertical component for districts III., YII. and YIII. 
A comparison of these discrepancies with those in Table lY. is interesting and may 
