80 Prof. L. Vegard: Results of Nortldight Investigations 



The value is probably considerably-smaller than 2*5 . 10 4 , 

 for we must remember that the photographic impression 

 of a ray may be spread out because the streamer moves 

 during the time of exposure. Further, the streamer is 

 necessarily produced by ray bundles of a certain cross- 

 section cIq, and — apart from scattering — the whole cross- 

 section d is approximately equal to the sum of d and 

 the diameter 2p of the circular orbit perpendicular to the 

 stream ers, or 



p — i(d—d ). 



The upper limit found for the quantity — must nearly 



correspond to the initial properties of the rays before 

 entering into the atmosphere ; there is no absorption 

 before luminosity sets in, and at the upper part of the 

 streamers the above-mentioned thickness can be measured, 

 and a ray would have to move a great many times round 

 the magnetic lines of force before its velocity was essentially 

 reduced. 



For the sake of comparison w T e will give the order of 



magnitude of — for the known types of electric rays : — 

 a-rays from radioactive substances : 



Positive rays produced in vacuum tubes : 



m 



< — ^4-25.10 6 <\ 



/3-rays from radioactive substances : 



1*8.10 3 :<— ^4-5.10 3 . 

 — e 



Cathode rays : 



0<~^0'5.10 3 . 



/m 



e 



mv 



The upper limit of — for the positive rays is calculated 



on the assumption that the ray has passed through a potential 

 of 90,000 volts, m is the mass, e the charge in electro- 

 magnetic units. 



We see from these numbers that the ordinary a-rays from 

 radioactive substances have a too small magnetic deflectibility 

 to explain the long and thin ray-streamers, and could only 

 produce such forms where either the luminous streamers are 



