534 MR. A. W. RUCKER AND DR. T. E. THORPE ON A MAGNETIC 
It is interesting to compare this table of the total secular change between the 
years 1886-91 with the table of rates of annual change given in our previous 
“Memoir” (p, 325), but it is hardly worth while to make the comparison at all the 
points of intersection of whole degrees of latitude and longitude. 
We have therefore prepared the following tables. In the first (Table XT.) a 
comparison is instituted at five points on longitude 4° W., which is nearly tLe 
central line of the United Kingdom. The first of the two numbers given for each 
element at each place is the annual secular change, taken from Table XII., p. 325, in 
our “ 1890 Memoir.” The second or lower number is obtained by dividing the corre¬ 
sponding quantity in Table XIV. by five. 
In Table XVI. a similar comparison is made at points on the same lines of latitude 
near the boundaries of the area of the survey. 
Table XV. 
Latitude. 
Longitude 4°. 
Declinatiou. 
Dip. 
Horizontal force 
(metric unit). 
o 
59 
8-4 
I'o 
0-0016 
7-9 
0-9 
0-0020 
57 
8-0 
1-2 
0-0018 
7-6 
DO 
0-0020 
7-6 
1-4 
0-0019 
o5 
7-3 
1-2 
0-0021 
53 
7-2 
1*6 
■ 
0-0020 
7-0 
1-3 
0-0021 
51 
6-8 
1-8 
0-0020 
6-8 
1-4 
0-0022 
