on the Direct Current Corona. 



293 



yet explained. But during the previous experiments 

 some observations have been made which suggest a close 

 relation between the corona discharge and the arc, and 

 which throw some light on the complicated nature of the 

 corona itself. In the following paragraphs a brief 

 account of some of these experiments will be given. 



Fig. 9. 



SILOVOLTS 



It has often been observed that an arc easily forms in 

 the tube when the line switch connecting the tube is 

 opened, especially when the wire in the corona tube is 

 positive and a fairly large current is passing in the 

 discharge. 



The Curve A, fig. 9, shows the current and arc-over 

 potential relation at different pressures for a corroded 

 steel wire 0-041 cm. diameter strung in a cylinder 3-63 cm. 



