Theory of the. Striated Discharge. 



99! 



nearly at their maximum value; and since the density of the 

 distribution of the electrons is inversely proportional to 

 the speed, these will be the places where the density of the 

 electrons is least. 



Thus, when a positive ion starts from such a place as P 

 (fig. 3) on the curve representing the distribution of energy 

 of the electrons, it will not at first be so likely to combine 

 with an electron and give out light as it will when it has 

 reached a place nearer the cathode where the energy of the 

 electrons is less and their number greater ; both these things 

 improve the chance of recombination and therefore of lumi- 

 nosity. Again, if the ion starts from the cathode side of the 



curve, it is moving towards places where the chance of 

 recombination is continually increasing ; whereas if it starts 

 from a point like Q on the anode side of the curve, as it 

 moves to the cathode, it will at first be moving to places where 

 the energy of the electrons is increasing and their density 

 diminishing, i. e. into places where the chance of recom- 

 bination is continually diminishing, and it is not until it 

 has passed P that its chance of recombination will begin 

 to improve. The result of this will be that the luminosity 

 will be far brighter on the half of the curve on the cathode 

 side than on the other half. The maximum of luminosity 

 will be on the cathode side of the maximum of ionization, 

 and the curves representing respectively the distribution of 

 energy of electrons and luminosity will be like those shown 

 in fig. 3, where the shaded portions correspond to luminous 

 patches. 



We see from the curves (1) and (3) that while the peaks of 

 the energy curves cover both maxima and minima values of 

 the electric force, the peaks of the luminosity curves include 

 maxima but not minima values of the electric force. This 

 is in accordance with all the measurements which have been 

 made on the distribution of the electric force in the striated 

 discharge. It will be seen from the slope of the X curves 

 that there is negative electrification on the cathode side of 



