SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY 1, 1886. 83 
In the case of twelve Scotch and six English stations we are able to compare the 
rate of change in the two periods 1837-1857 and 1857-1886. The data are taken 
from the sources above described. 
Station. 
Mean anuual decrease of inclination. 
Ratio. 
1837-1857. 
1857-1888. 
Lerwick. 
1-65 
0-96 
1-72 
Aberdeen. 
2-02 
1-33 
1-52 
Kirkwall. 
1-97 
1-07 
1-84 
Wick. 
2-02 
ITl 
1-82 . 
Golspie. 
1-68 
1-.38 
1-22 
Inverness. 
1-92 
1-37 
1-40 
Fort Augustus. 
1-80 
1-21 
1-49 
Edinburgli. 
1-82 
1-14 
1-60 
Glasgow. 
1-80 
142 
1-27 
Helensburgh. 
1-48 
1-32 
1T2 
Campbelton. 
1-99 
1-39 
1-43 
Cumbrae. 
1-53 
0-94 
1-63 
Berwick. 
2-48 
1-33 
1-87 
Scarborough. 
2-02 
1-63 
1-24 
Stonyhurst. 
. . 
1-75 
. . 
Cromer. 
2-22 
1-44 
1-54 
Cambiudge. 
2-50 
1-58 
1-58 
Lowestoft. 
2T7 
1-54 
1-41 
Kew. 
2-65 
1-62 
1-63 
St. Leonards. 
1 82 
Plymouth. 
2-73 
1-89 
1-44 
The mean ratio for North Scotland is 1’57, for South Scotland 1'49, and for 
England 1'47. 
These figures prove that the ratio of the m.ean annual decrease, in the intervals 
1837-57 and 1857-87 has been nearly constant all over Great Britain, but that the 
rate of change has been rather more rapid in the north. 
If we assume that the ratio has been 15 for England and Ireland, we may 
deduce x, the mean annual decrease between 1857-87, from the corresponding 
quantity given in Table II., p. 82, for the interval 1837-87, by the formula 
1'5 X 20x + 2)0x = 50(7, 
X — 5(7/6. 
The same quantity is determined for stations in Scotland bv direct experiment by 
the comparison of our own observations with those of Mr. Welsh. The results are 
given in the following Table. 
■M 9. 
