1904.] On the Electric Equilibrium of the Sun. 



499 



as assumed above, we find that electrons moving with the velocity of 

 light are caught by the sun, if the asymptote of their hyperbolic path 

 is less distant from the sun than 2420 times the mean distance of the 

 earth from the sun (or one twenty-fourth of a light-year). This limit 

 distance is inversely proportional to the velocity of the electrons, and 

 nearly proportional to the square-root of the charge of the sun. As 

 now, according to the researches of Lenard, the electrons from a 

 negatively electrified body possess a much less velocity than light, this 

 distance is really much greater than that just calculated. 



If, for instance, the velocity of the electrons is the thirtieth part of 

 that of light, a number that is in good agreement with Lenard's 

 measurements, all electrons from space which came along a path 

 that is less distant than 1'25 light-year from the sun, will be caught by 

 the sun. Of course the electrons move with different velocity, so that 

 the said distance may only be regarded as a mean, or as representing 

 the order of magnitude. 



Now our nearest star (a Centauri) is distant from us by about 

 4 light-years, and other stars lie within less than 10 light-years. 

 Thus it is evident that the negative electrons, which are sent off 

 from aggregates of negatively charged drops (these aggregates are 

 probably identical with what we call cosmic dust or meteorites), can 

 in general not pass by many suns without being caught by them. 

 And on the other hand the suns recover in mean from space as 

 much negative electricity as they lose. The electric charges of 

 the suns are in this respect very effective regulators. If the charge is 

 quadrupled the mean distance of the caught electrons is doubled, or, 

 in other words, as they are uniformly disseminated in space, their 

 quantity is quadrupled. Therefore the supply of negative electricity to 

 the suns is proportional to their defect thereof. 



From these considerations we see that a very effective balance of 

 gains and losses of negative electricity is maintained. Evidently this 

 balance depends upon the supposition that for the particles that drive 

 away from the sun, other forces than the electric, viz., the pressure of 

 radiation, are preponderating, whilst for the negative electrons caught 

 by the sun, other forces than the electric are wholly insignificant 

 compared with these. 



If one supposed, as some authors do, that the negative electricity 

 was carried away from the sun by means of cathode rays, an effective 

 circulation like that described above would be wholly impossible. 



VOL. LXXIII. 



