246 



WHITEHEAD— HIGH VOLTAGE CORONA IN AIR. 



the surface of the conductor and more so the smaller its radius of 

 curvature, and also in that the value of electric intensity at which 

 corona first appears may be much higher than 32 kilovolts per cen- 

 timeter. In fact in these cases values of electric intensity higher 

 than 32 kilovolts per centimeter are reached with no resulting 

 evidence of breakdown or brush discharge. 



Evidently we are here in the presence of a striking property of 







^Uv 



^s! 



^ft- 



^-.-^ 





T= volts, 



E^ ~ SLirfcice intensitif. 



00 



£•= ? 



Fig. I. Spark and Corona. 



the air showing a definite influence of the volume of air subjected to 

 electric strain on the intensity at which initial breakdown takes place. 

 It would appear that here is a splendid opportunity for further 

 study of the molecular and atomic structure of the air. The phe- 

 nomena are extremely definite and constant in the case of the 

 central wire and cylinder, and all of the conditions are susceptible 

 of accurate measurement. However the physicist appears not to 

 be interested in the electric properties of air at pressures in the 

 neighborhood of that of the atmosphere. Professor J. T. Town- 



