CONTEMPORARY ADVANCES IN PHYSICS 



105 



most recent work: it is a set of Fs-vs-p curves for various frequencies 

 of an extremely wide range (the wave-lengths in meters are marked 

 beside the curves) obtained with a tube 10 cm. long closed at its ends 

 by flat plates, covered outwardly by sheets of tinfoil serving as the 

 electrodes. (Gutton never indicates the actual observations on his 

 graphs.) It is superfluous to say that this family of curves is easy 

 neither to envisage nor to describe. Most of them are of the type 



500 r 



LOG ^ 



Fig. IS^Onset-potential vs. (logarithm of) wave-length, for self-sustaining glow at 

 the indicated pressures. (H. Gutton.) 



familiar from other researches, with a single flattish minimum; but 

 some are very different, with no minimum at all in the range of experi- 

 ment, but a couple of sharp bends with a linear segment between. 

 The Vs-'vs-v curves for various pressures, exhibited in Fig. 18, form a 

 set even more confusing. 



Over the frequency-ranges where the curves of Fig. 17 have single 



