igii.] 



WHITEHEAD— HIGH VOLTAGE CORONA IN AIR. 



389 



in which E is the maximum value of the potential difference between 

 wire of radius r and outer cyhnder of radius R, and which in this 

 case is the effective voltage multipHed by 1.46. Expressed in terms 

 of electric intensity at which corona begins, in kilovolts per centi- 



PrCSSURE (MM.Hq.) 



Fig. 6. 



meter, and pressure in centimeters of mercury, the equation for the 

 .152 cm. wire is : 



d{KV) 



dr 



and for the .276 wire 



d(KV) 

 dr 



15-2 + •673/'. 



= 11. 6 + .595/', 



(3) 

 (4) 



