MUTUAL IMPEDANCE OF GROUNDED WIRES 287 



E = grad div II - Ti'll, (10) 



where \\ is the propagation constant in the air. We can now allow 

 Fi to vanish, thus obtaining the expression for the field corresponding 

 to the assumptions of our problem. We then proceed as before to 

 lind the exjiression for the mutual impedance. 



I am greatly indebted to my colleagues, Dr. Marion C. Gray and 

 Miss Helen M. Kammerer, for much valuable assistance in the 

 preparation of this paper, particularly in the compilation of the tables 

 and curves. 



