S()Mn coNiEMi'OK.iRv .ii>r.i.\ii:s i\ rinsus ii i-w 



it attains values just in front of the riir\i(l I'li-iMrtiile (or elci'trotk's, 

 if liolh arc iiirvi"<l) so ^real that if thi'\ prevaik'il over an equal inter- 

 space Iiotween flat electrodes they would instantly provoke an explosi\e 

 sp.irk. In some cases the glow in a diiise gas reseinhles a very ron- 



Fig. 12 — The glow in air at atmospheric pressures, near a curved electrode (ihe 

 otlicr electrorie is a plate beyond the top of the picture). In 1, 4 the curved electrode 

 is the anode; in 2, 3, 5, 6 it is the cathode. (J. Zelcny, Physical Review) 



tracted and reduced copy of portions of ilie ylow in a rarefied, gas. 

 Thus in the photographs (Figs. 12, 13) of the luminosity surrounding a 

 very ctirved cathode, it is possible to discern two dark spaces and two 

 h)right ones, the first dark space lying just outside the cathode, the last 

 bright region fading off intcj the darkness which extends away towards 

 the Hat anode (far above and out of the picture). In the pictures of the 

 glow surrounding a very curved anode, we see only a luminous sheath 



