and JSature of the Cosmic Electric Rays. 75 



With these problems we meet with the difficulty that our 

 knowledge of the composition of the higher strata of the 

 atmosphere is very imperfect. Even if we suppose that 

 one gas varies independently of the other according to 

 Dal ton's law we are still wanting the knowledge about 

 the temperature distribution, and although a variation of 

 temperature has a comparatively small effect on the atmo- 

 sphere near the ground, the effect may be very large 

 indeed at heights of the order of 100 km. The calculations 

 performed with regard to the absorption of electric rays 

 in the atmosphere have, in accordance with Wegener *, 

 been based on the following assumptions: — 



(1) Each gas varies with the height as if in equilibrium 



when the others were not present. 



(2) For the first 10 km. above the ground the average 



temperature is put — 23° C. Above this height 

 we put the mean temperature equal to —55° C. 



Under these conditions, the pressure at a given height 

 h > 10 km. is given by the expression 



, n _ ,. ,,0-694 . 10-2 M - 5-415 . 10~ 8 Mh 



jj JJQC . tf , 



where M is the molecular weight of the gas considered, 

 and po the partial pressure of the gas at the surface of 

 the earth, and 



Po = ^ 1-0133. 10'^, 



r 100 cm. 



where x is the number of volume per cent, of the particular 

 gas in the atmosphere near the ground. Wegener gives 

 the following values of x for the different constituents : — 



Gas. M. x. 



Geocoronium (hypothetical) ... 0'00058 



Hydrogen 2*01 0'0033 



Helium 4 0-0005 



Nitrogen 28 78*1 



Oxygen 32 20'9 



Argon 39-9 0'93 7 



Of these gases, geocoronium is quite hypothetical and 

 a calculation has little or no value. Further, the gas 

 argon will have practically no effect in the higher strata 

 of the atmosphere, on account of its great molecular weight 

 and the small concentration. The pressure in dyne cm. 1 



* A. Wegener, Physik. Zoitschr. xii. no?. 5 & (1911). 



