26 
THE REV. STEPHEN J. PERRY ON THE MAGNETIC 
Rev. J. Hawett, S.J., without whose assistance in reducing and verifying the results I 
should have been forced to delay the presentation of these pages for a very considerable 
time. 
Appendix. 
In order to determine with greater exactness the secular variations of the Isoclinals, 
Isodynamics, and Isogonics, the values for 1858 have been calculated from Lamont’s 
data by the same process as that adopted for the survey of 1868 and 1869. The data 
taken from Dr. Lamont’s ‘ Untersuchungen iiber die Richtung und Starke des Erdmag- 
netismus ’ are contained in the following Table. 
Table XXI. 
Station. 
Latitude. 
Longitude. 
Dip. 
H. E. 
Declination. 
O 
44 
12 
48 
m 
6 
8 
53 
63 
21-6 
2-0491 
O 
19 
15-1 
49 
47 
53 
24 
0 
4 
1-8277 
1-9112 
19 
56-3 
28 
2 
11 
37 
65 
55-9 
20 
16-3 
45 
38 
34 
8 
45 
64 
39*1 
1-9899 
19 
50-2 
50 
16 
47 
1 
46 
67 23-2 
1-8201 
43 
29 
12 
15 
19 
63 
6-8 
2-0691 
19 
57'8 
47 
44 
37 
37 
13 
18 
1 
1- 9545 
2- 0163 
17 
20 
11-7 
0-2 
50 
11 
27 
64 
5-8 
45 
18 
0 
4 
12 
63 
44-3 
2-0321 
18 
21-9 
43 
24 
36 
5 
24 
2-1173 
1-9527 
17 
19 
7*9 
22'0 
46 
48 
14 
2 
31 
65 
6-9 
45 
46 
22 
3 
0 
64 
12T 
2-0068 
18 
34-1 
48 
45 
54 
13 
1 
1-9044 
1-9543 
47 
19 
53 
10 
46 
64 
55-0 
17 
55-9 
51 
1 
33 
0 
5 
67 
56-3 
1-7871 
20 
6-6 
49 
2 
52 
6 
27 
66 
35-6 
1-8790 
48 
26 
8 
0 
41 
66 
16-0 
1-8886 
44 
37 
24 
13 
22 
63 57T 
2-0235 
45 
9 
39 
11 
9 
25 
2-0064 
19 
20 
46-3 
44 
38 
13 
57 
63 
59*8 
2-0222 
3-9 
47 
59 
34 
8 
39 
66 
13-0 
1-8903 
20 
25-7 
45 
9 , 
46 
6 
12 
2-0473 
1- 9870 
2- 1363 
45 
50 
3 
4 
21 
19 
17 
23-8 
43 
17 
45 
12 
15 
61 
40-5 
4-1 
48 
57 
2 
2 
11 
66 
24-2 
1-8765 
19 
16-4 
43 
53 
18 
11 
19 
63 
19-0 
2-0557 
19 
40-3 
44 
33 
18 
9 
36 
62 
53-3 
2-0750 
17 
35-5 
43 
36 
44 
6 
10 
62 
15-3 
2-1112 
46 
34 
04 
3 
56 
64 
43-4 
1-9758 
18 
39-2 
48 
41 
17 
24 
15 
19 
35 
1-8985 
17 
45-6 
47 
12 
15 
65 
55-9 
1-9096 
20 
57*8 
43 
11 
8 
2 
38 
62 
6-4 
2-1184 
18 
1-1 
44 
8 
42 
9 
52 
62 
36-9 
2-0931 
17 
27-7 
47 
54 
9 
1 
42 
65 
52-6 
1-9079 
19 
25-4 
48 
50 
13 
0 
0 
66 
26-5 
1-8759 
19 
36-3 
45 
10 
32 
6 
29 
15 
2-0149 
19 
26-5 
42 
42 
9 
2 
61 
47-8 
2-1357 
17 
59-2 
46 
34 
31 
7 
58 
65 
8-3 
1-9523 
19 
56-4 
48 
43 
57 
33 
18 
53 
1-8989 
17 
18 
14-6 
43 
36 
3 
35 
62 
46-1 
2-0861 
45-0 
45 
3 
57 
10 
1 
63 
18-2 
2-0543 
17 
40-9 
47 
23 
5 
6 
36 
65 
44-3 
1-9192 
19 
54-4 
47 
37 
3 
15 
14 
1-9496 
17 
28-8 
Agen 
Amiens 
Angers 
Angouleme 
Arras 
Bayonne 
Belfort 
Bordeaux 
Brioude 
Cette 
Chateauroux 
Clermont Ferrand 
Commercy 
Dijon 
Dunkirk 
Epernay 
Etampes 
Lamothe 
La Roche Chalais 
La teste de Buch 
Le Mans 
Le Puy 
Limoges 
Marseilles 
Meaux 
Mont de Marson 
Montelimart 
Montpellier ...... 
Moulins sur Allier 
Nancy 
Nantes 
Narbonne 
Orange 
Orleans 
Paris 
Perigueux 
Perpignan 
Poitiers 
Sarrebourg 
Toulouse 
Tournon 
Tours 
Vesoul 
The Horizontal Force is expressed above in the French units of the millimetre, the 
milligram, and the second of mean solar time. Its value is found from the formula 
