170 M. W. Siemens on the Admissibility of the 
surrounding the sun, and the corresponding great differences 
in temperature and density, since the electricity of the outer 
layers of the photosphere would then pass over to the products 
of combustion, and with them, according to my brother's 
theory, would in part be spread in the direction of the plane 
of rotation of the sun in cosmical space. Even supposing, 
however, that the process of electrification may have to be sought 
in the solar combustion itself, in the friction of the matter 
flowing in from cosmical space, or in other causes yet unknown, 
the possibility of the existence of an electric potential of the 
sun is given by the equatorial diffusion of solar products of 
combustion in cosmical space. 
And this possibility rises to the rank of high probability 
when one considers the facility with which some difficult and 
hitherto unsolved problems of terrestrial phenomena can be 
solved with the aid of a solar electric potential. If the sun 
possesses a high electric potential, he must act distributively 
upon all the celestial bodies, consequently upon the earth also. 
But an accumulation of electricity upon the entire solar 
surface can only take place when the opposite electricity 
liberated is conducted away ; and the only conceivable way 
in which it can be so conducted is by being diffused in 
cosmical space. The process is approximately the same as 
that which takes place when an insulated sphere is placed 
opposite to a larger charged spherical conductor. The sphere 
then gradually takes an opposite charge, while the same 
electricity is lost by dissipation in space. With the earth this 
dissipation of the so-called free electricity arising from the 
sun's distribution is, moreover, greatly favoured by the 
extreme rarefaction of the upper strata of air and by the 
ascending and descending currents of air loaded with moisture, 
since by these the free electricity is conveyed to the upper 
strata of highly rarefied air. That in this rarefied upper air 
electric currents take place is proved by the aurora boreales 
and australes. They might be regarded as the electrical 
compensation taking place at the boundary of the earth's 
atmosphere, between the matter flowing out from the sun 
charged with negative electricity and the liberated positive 
induced electricity of the earth. This compensation must 
occur whenever by a change in the sun's potential that of the 
earth is also changed. For the restoration of equilibrium, 
positive or negative electricity must then flow out from the 
earth ; consequently either a compensation must take place at 
the boundary of the atmosphere with the negative electricity 
flowing out from the sun, or this must flow to the earth. The 
reason that this exchange takes place preeminently in the 
