400 Transactions of the Boy at Society of South Africa. 
Table V. 
Pietermaritzhurg, October 1st. 
Time. 
Pot. Grad. 
Time. 
Pot. Grad. 
Time. 
Pot. Grad. 
5.30 
100 
6.10 
140 
7.0 
160 
5.40 
114 
6.20 
120 
7.15 
188 
5.50 
108 
6.30 
120 
7.30 
205 
5.55 
120 
6.40 
135 
7.45 
230 
6.0 
135 
6.50 
140 
8.0 
260 
Pietermaritzburg is 2,200 feet above the sea-level and lies in a hollow, 
the hills rising to over 5,000 feet. From Pietermaritzburg a journey was 
made to Howick, 3,440 feet above sea-level. This was reached at 10 a.m. 
At Howick there is a waterfall on the Umgeni Eiver, which drops sheer 
down for 360 feet, and gives rise to a considerable cloud of spray, and 
this, as anticipated, from comparison with the Victoria Falls, was the seat 
of a large amount of negative electrification. The fall is about 2| miles 
from the railway station, and observations were taken as nearly as possible 
along the straight line joining the station and the fall. At about 2 miles 
from the fall the gradient was 200 volts per metre, and steadily diminished 
as the fall was approached. The electrification was of course positive in 
sign. At 350 yards from the fall the electrification was zerOf and on 
getting nearer the fall the potential rose rapidly, reaching a very high 
negative value, probably 2,000 volts per metre, at the edge of the chasm. 
The shape of the gorge enables one to take observations for more than 
half of a circle round the fall as a centre, and also at Stockdale on the side 
opposite to the fall. 
During the observation a distant thunderstorm was raging, and when 
the electroscope was on the zero line each flash was accompanied by a 
sudden rise in the potential to + 60 volts, but on a httle rain falUng the 
potential rose to a higher negative value. 
Between Pietermaritzburg and Durban observations were prevented 
by rain. At Durban the potential was very high even during the after- 
noon, and at 7 p.m. reached the value of about 350 volts per mile on the 
beach, and close to the dock over 400 ; the high value at the latter 
place being due to the clouds of steam emitted by several vessels in 
the port. 
The following morning a rapid journey was made from Umbilo to 
Umgeni via Durban, between the hours of 7.30 and 8 a.m. These places 
are at practically sea-level, but are a little way inland, and the object was 
to ascertain whether the potential gradient was constant over a distance 
