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Cady and Yinal — Electric Arc. 



I. Theory of the glow-arc oscillations (§§2 to 7). 

 II. Best conditions for the production of the oscillations 

 (§§8 to 12). 



III. Experimental evidence of the existence of glow-arc 

 oscillations (§§13, 11). 



IV. Properties of the oscillations (§§ 15 to 32). 



I. Theory. 



§ 2. For the sake of clearness the theory which offers the 

 most satisfactory explanation of the oscillations is set forth. 



Fig. 1. 





I 



here, the experimental evidence in its favor being for the 

 most part reserved until later. 



Let us suppose that we have a circuit consisting of an 

 electromotive force of several hundred volts, large resistance 

 capable of fine adjustment, and a short gap between metallic 

 terminals in free air. Then, as is well known, the discharge 

 will be either in the form of a glow, with a characteristic curve 

 represented by the line ah in fig. 1, or an arc, represented 

 by cd. he' is the unstable interval over which the discharge 



