410 SCIENTIFIC WRITINGS. 



the colossal dimensions of the sun in comparison with 

 those of the earth the sun's potential will call forth 

 by electric distribution a terrestrial potential of nearly 

 half the amount, if we assume, that the electricity, 

 becoming free at the earth's surface, and similar to 

 the solar electricity, is absorbed through radiation 

 and neutralization by the electricity of the oppositely 

 electrified matter, proceeding according to brother 

 William's theory from the sun in the direction of the 

 sun's equator. That this high electric tension is not 

 observed at the earth's surface is a consequence of 

 the size of the earth's radius. Now by the rotation 

 of the earth the electricity bound to the earth's surface 

 by the solar electricity is carried round the earth, and 

 thus produces the effect of an electric current circling 

 round it. which makes it magnetic. Just as the earth's 



o 



magnetism, so also the terrestrial currents and polar 

 lights find their explanation by the electrical solar 

 potential, and similarly the reaction of phenomena in 

 the sun, such as the occurrence of sun-spots and 

 coronae, on terrestrial phenomena becomes explicable, 

 if we conceive them intimately connected with changes 

 of the sun's potential. Atmospheric and lightning elec- 

 tricity likewise find their explanation through the 

 electrical solar potential. 



Under the title "Contributions to the theory of 

 electro -magnetism" I communicated two dissertations 

 to the Berlin Academy in the years 1881 and 1884, 

 in which the theory of magnetism was considerably 

 extended, and parts of it, that had hitherto remained 



