ME. C. V. WALKEE ON MAGNETIC CALMS AND EAETH-CUEEENTS. 
205 
nexion witli the earth E. A brass plug is provided, which fits into the respective holes 
1, 2, and 3. When in the centre hole 1, this instrument is not in action ; when in the 
hole 2, it connects 1 and 2 together, so that the wire on the a or Dover side of the 
galvanometer is in direct communication with the earth E, and the galvanometer is in 
circuit between London and Tonbridge ; when the plug is transferred to the hole 3, for 
like reasons the galvanometer is in circuit between Tonbridge and Dover. Observations 
on the whole line, or on either of the two sections, are readily and rapidly obtained by 
this arrangement. 
The coil of the galvanometer is for convenience so wound, that when it is traversed 
by a positive current of electricity travelling towards London, or, to use railway lan- 
guage, “up” the line, the index moves in the right quadrant, or toward the word “up” 
engraved there; wLen, on the other hand, it is travelling /’row London, or “down” the 
line, the index moves to the left quadrant, or toward the word “ down.” 
The following is a Table of Observations made during October 1861. They are 
taken in the order of the columns 1, 2, and 3. The letters u ox d are entered against 
each observation, according as the index moves to the word “ up ” or “ down.” The 
time is taken at the end of the third observation. It is given in “ Greenwich Mean 
Time,” fractions of minutes being rejected ; the local clock error being known by means 
of the “ Time Signals ” that come two or three times a day from Greenwich. 
Table XIII. 
Directions and Values of Earth-currents, collected at Tonbridge, 1861, October; from 
the London-Dover ; — London-Tonbridge ; — and Tonbridge-Dover lines. 
Date. 
Time. 
Column 1. 
Column 2. 
Column 3. 
Date. 
Time. 
Column 1. 
Column 2. 
Column 3. 
Dover-Londou «. 
London-Dover d. 
Tonbridge-London ...«. 
London-Tonbridge ...d. 
Dover-Tonbridge u. 
Tonbridge-Dover d. 
Dover-London w. 
London-Dover d. 
Tonbridge-London ...it. 
London-Tonbridge ...d. 
Dover-Tonbridge it. 
Tonbridge-Dover ... 
1861. 
h m 
1861. 
h m 
O 
O 
Oct. 
1. 
9-31 A.M. 
1§ M 
14 m 
Oct. 4. 
12.26 P.M. 
40 M 
55 M 
50 M 
11.42 a.m. 
15 It 
35 d 
30 u 
4.50 p.M. 
10(7 
20 d 
2d 
2.20 p.M. 
4 u 
36 
Oct. 5. 
7.44 A.M. 
35 d 
50 (7 
45(7 
2.35 p.M. 
3 u 
23 d 
7u 
Oct. 8. 
11 A.M. 
20 d 
10(7 
31(7 
Oct. 
2. 
9.34 A.M. 
9 u 
4(7 
11m 
12.56 p.M. 
20 M 
15 m 
15 m 
12.24 p.M. 
23 u 
26(7 
42 M 
1.47 P.M. 
45 M 
10(7 
50 M 
2.15 p.M. 
17 M 
35 d 
20 M 
3.12 p.M. 
48 M 
50(7 
55 M 
2.47 P.M. 
0 
0 
0 
o 
O 
6.20 A.M. 
12 m 
20(7 
25 m 
3.20 p.M. 
6 u 
28(7 
18m 
9-20 A.M. 
35(7 
25 m 
35 d 
3.35 p.M. 
0 
5(7 
0 
Oct. 10. 
6.58 A.M. 
10 m 
15(7 
20 u 
Oct. 
3. 
7.2 A.M. 
35 d 
5 d 
20(7 
3.14 p.M. 
30 M 
50(7 
50 M 
1 1.44 A.M. 
32 u 
14(7 
38 M 
10.0 p.M. 
55(7 
5 M 
10(7 
5.20 p.M. 
19d 
3d 
20(7 
Oct. 11. 
6.25 A.M. 
55 M 
50(7 
55 m 
10.12 p.M. 
20 u 
0 
20 m 
9-6 A.M. 
55 d 
35 M 
50(7 
Oct. 
4. 
6.25 A.M. 
33 d 
3 u 
45(7 
10.25 A.M. 
0 
30 M 
0 
12.24 p.M. 
35 u 
29 e7 
50 M 
Oct. 12. 
7-8 A.M. 
6 M 
40(7 
40 M 
