464 Proceedings of the Koyal Society of Edinburgh. [Sess, 
100 volts by means of small accumulators. The field, about the same 
magnitude as the earth’s normal field, was thus very steady, and not liable 
to fluctuations as when the earth’s field was used. The dissipation factors 
for the test-plate and turf did not differ by more than 5 per cent. More 
detailed experiments are being made on this point. 
The following tables give the results of the observations : — 
Table I. 
Date. 
Time. 
Number 
of 
Observa- 
tions. 
Charge per 
sq. cm. 
E.S.U. 
Current per 
sq. cm. 
E.S.U. 
Dissipation 
per cent, 
per min. 
Potential 
gradient 
volts per 
metre. 
1909. 
1 
May 
24 
1.42-3.12 p.m. 
13 
55T x 10 - 5 
I *34 x 10 -5 
•66 
i 207 
26 
12.29-2.11 „ 
5 
43-0 
55 
1 .27 
55 
•72 
163 
28 
3.25-3.39 „ 
3 
24-2 
55 
j -26 
55 
1-01 
92 
June 
1 
2.45-3.15 „ 
5 
55*6 
55 
•48 
55 
•89 
210 
1 
4.01 
1 
39-0 
55 
•12 
55 
•30 
147 
55 
3 
2.40-2.52 „ 
2 
60-5 
55 
•74 
55 
1*23 
228 
Means 
46*2 
)5 
•37 
55 
•80 
175 
Table II. 
May 
26 
2.33-2.54 p.m. 
3 
41*3 x 10 ~ 5 i 
•23 x 10-£ 
•56 
156 
June 
1 
3.22-3.57 „ 
5 
50-3 
1 
55 
•40 
55 
•82 
189 
| 
55 
2 
2.33-3.08 „ 
4 
28-9 
55 
•00 
55 
•00 
109 
1 55 
3 
1.57-2.36 „ 
5 
63-5 
55 
•57 
55 
•91 
239 
55 
3 
2.57 3.08 „ 
2 
78-9 
55 
•89 
55 
1T4 
298 
55 
4 
2.48-3.51 „ 
3 
33-9 
55 
•27 
55 
•77 
128 
55 
7 
2.11-3.06 „ 
3 
363 
55 
•32 
55 
•83 
137 
55 
15 
2.32-3.47 „ 
3 
47-2 
55 
•58 
55 
1-21 
178 
Means 
47-5 
)5 
•41 
55 
•79 
179 
Table 
III. 
June 
17 
2.51-4.16 p.m. 
12 
64-4 x 10 ~ 5 
•83 x 10 -5 1 
1-29 
241 
55 
17 
6.13-6.46 „ 
5 
48-6 
5 ) 
•92 
f 
1-92 
184 
Means 
56-5 
5 ? 
•87 
55 
1-60 
212 
Table IY. 
June 
1 
9.39-10.21 p.m. 
3 
95-2 xlO - 5 
1-47 x 10 - 5 
1-54 
359 
55 
8 
9.00-10.59 „ 
16 
100-2 
55 
3-59 
55 
3-58 
377 
55 
15 
9.17-10.49 „ 
11 
88-9 
55 
2-68 
55 
3-04 
335 
Means 
94-8 
2-58 
55 
2-72 
357 
