and Nature of the Cosmic Electric Rays. 73 



heights of 90-100 km., and then I think we are justified 

 in concluding that rajs of this kind, which at the absence 

 of the atmosphere would return to space at a height .some- 

 what greater than 100 km., will on an average turn back 

 at the same height even when the atmosphere is present, 

 and may have sufficient penetrating power to get out of the 

 atmosphere and back to space; and it is quite legitimate — 

 as previously done — to assume that numbers of rajs under 

 certain conditions maj be as it were driven out of the 

 atmosphere bj the effect of the magnetic field. 



With regard to the luminosity distribution, the magnetic 

 field will have a similar effect as if a heterogeneous beam of 

 rays were moving down the atmosphere without an influence 

 of fields of force. In the latter case rajs of different pene- 

 trating power will be completelj absorbed at various distances 

 from the ground, and the luminosity distribution will vary 

 with the composition of the ray mixture. In a similar way 

 the magnetic field may turn back the rays or cause them 

 to be absorbed at various distances from the ground, and 

 according as these turning points distribute themselves on 

 the various height intervals the corresponding luminosity 

 distribution may vary. 



The consequences which we were able to draw with regard 

 to the orbit of a ray moving in the field produced by a single 

 magnetic pole immediately apply to a uniform magnetic field, 

 because we only have to imagine the pole moving towards 

 infinity. The orbits of an electric ray moving in an uniform 

 field will be a geodetic line on a cylinder, which in the case 

 of an absorbing medium no longer has a circular cross- 

 section, but the latter will have the form of a spiral. 



§ 7. Absorption of Positive Rays in the Atmosphere. 



Before proceeding to see what consequences are to be 

 drawn from the luminosity distribution regarding the nature 

 of the cosmic electric rays, we shall briefly consider the 

 absorption of positive rays in the atmosphere. 



This problem has been solved by the author in 1911*. In 

 papers published in 1916 I showed how to determine the 

 luminosity distribution produced b}' positive rays, and the 

 solution of this absorption problem also involves the deter- 

 mination of the velocity of the positive ray at any point of 

 its pathf* 



* L. Vegard, "On the Properties of the Radiation producing Aurora 

 Borealis," Arch. f. mat. fy nat. vid. 1911 ; Phil. Mag. Fob. 1912. 

 t In a note in C. JR. clxx. p. 742, for March L920, Prof. Stefcmer has 



also treated this problem. 



