Assumption of a Solar Etectric Potential. 173 
oxygen of the air, that this oxygen is the seat of the earth's 
magnetism, if calculation had not already shown that the seat 
of this magnetism cannot be outside of the surface of the 
earth. Just as little can those theories of the earth's mag- 
netism meet with consideration which rest upon thermo- 
electric currents or, as Zollner attempted to base his, on 
convection-currents in the liquid interior of the earth, since 
in a medium conducting equally well in all directions such 
currents can never take place. Moreover no cause can be 
found for the existence of permanent regular currents of the 
liquid interior of the earth. 
In like manner as an electric potential of the sun affords 
the possibility of accounting for the earth's magnetism, to- 
gether with the related phenomena of the auroras and earth- 
currents, it also gives a handle for the explanation of the 
electricity of the air and the phenomena of thunder-storms. 
That the earth must be charged with negative electricity 
was assumed already by Lamont for the explanation of the 
perpetually changing atmospheric electricity. His view, 
however, that this electric charge is to be accounted for by 
thermoelectric differences, is no more tenable than the view 
that friction-processes can generate an electric potential of 
the earth. Such a potential can only arise from cosmic 
influence and the removal of the liberated same electricity 
by diffusion in space, or its neutralization by the oppositely 
charged matter which flows out from the sun in the direction 
of the plane of his equator. If, however, we assume this to 
be the case, that consequently the earth together with the 
sun forms an electric accumulation-apparatus the separating 
dielectric of which is the atmosphere of the sun and of the 
earth and the interplanetary space filled with most highly 
rarefied matter, all the conclusions drawn by Lamont and 
others from the electric charge of the earth are justified. 
But to account for the electricity of thunder-storms, the 
trifling and varying electricity of the atmosphere, to which 
it has hitherto been attributed, does not seem sufficient. 
The sudden appearance of such vast masses of electricity as 
arrive especially in tropical storms repels the supposition that 
they have had their seat in the feeble electric charge of the 
comparatively small quantity of air that carries the thunder- 
clouds. The sources from which it springs must be more 
productive. Such a source, of inexhaustible vastness, is 
found in the electric charging of the earth by solar influence. 
When a conducting object is brought near a large sphere 
charged with electricity, it is subjected to the distributive 
action of the electricity existing on the surface of the sphere. 
