THE ELECTRIC ARC 



arc is much less than that needed for carbon arcs. Scarcely 

 any measurements have been published regarding this, 

 but a few observations have been recently made by my- 



70 



60 



50 



040 



30 



20 



10 



16 



20 



4 8 12 



LENGTH IN MM. 

 FIG. 15. 



self and are given in Fig. 15. With different settings for 

 length the readings of the voltmeter varied by one or two 

 volts, but by taking several observations an average was 

 found which represents closely the correct value. 



Curve a in Fig. 15 represents the voltages for different 



