Assumption of a Solar Electric Potential. 175 
contrary electricity to that of the earth, while the upper 
part is electrified similarly to the latter. But a dense con- 
ductive bank of clouds may in one or more places come into 
conductive connexion with the earth itself. It then forms a part 
of the earth's conductive surface, and takes up its electricity*. 
The latter process most readily occurs at the declivity of steep 
mountains against which the layers of cloud rest. Hence 
mountaiDS frequently occasion tempests. In the generation 
of the clouds that carry the electricity of storms electricity does 
* During a voyage on the Mediterranean in the winter of I860, in the 
vicinity of the Spanish coast, between Cartagena and Almeida I had an 
opportunity of observing the course of the phenomenon of a waterspout, 
which appears to me to tell decidedly in favour of this conception. 
Between the ship and the coast in the vicinity of Alnieria, v* ith a vigo- 
rously agitated so-called dead sea, without any considerable motion of the 
air, a dense but apparently not high bank of black clouds was seen, under 
which the sea seemed to be in the wildest commotion. It appeared there 
like a roundish white spot, the diameter of which the seamen estimated 
at from two to three [German] nautical miles, foaming up to a great 
height, while the sea around it showed only smooth waves without any 
breakers. In spite of the considerable distance of the ship from the place 
of violent agitation, amounting to several leagues, it could be distinctly 
seen through the telescope that the angry surges rose several metres above 
the sharply denned surface of the relatively calm mirror of the sea. The 
cloud descended at one place in the shape of a funnel, forming a streak 
of cloud curved like an elephant's trunk, reaching down nearly to the 
foaming surface of the sea, and apparently joining below. Perfect con- 
tact with the foaming surface could not be perceived ; and, what was 
surprising, no greater foaming took place under the trunk-shaped cloud 
than in other places. The trunk itself slowly rotated, if I remember 
rightly, in the direction of the hands of a watch, over the white spot ; and 
its place of junction with the cloud took part in the motion, though not 
to an equal extent. Unfortunately, night coming on and the increasing 
distance, after about half an hour's observation, during which the trunk 
had made a turn and a half, keeping its point constantly at about one 
third of the radius of the white spot from its margin, deprived us of the 
further contemplation of this interesting phenomenon, which had been 
followed with the closest attention by myself, my brother William and 
his wife, and the naval officers belonging- to the company of the French 
cable-ship, on board of which we were. No whirling motion was per- 
ceptible. Alm ost a dead calm prevailed. It can only have been a purely 
electrical phenomenon, which must have consisted in an electric current 
from the earth to the cloud. If we assume that this current had at one 
place become so strong that, by electric conveyance of the liquid, a- con- 
ductive water communication between the sea and the cloud was formed, 
the rotation of the trunk under the" influence of the earth's magnetism is 
also explained. During the night a storm raged on the Spanish coast, 
which probably originated in the waterspout observed by us. The latter, 
however, appeared later to have directed its course from the Spanish to the 
African coast ; for towards the end of the night our ship near the latter 
coast encountered so fearful a storm of only a few minutes' duration that 
it was in the greatest peril, and the seamen were firmly of opinion that the 
waterspout had passed over the ship. 
