428 



DR. T. R. LYLE ON THE SELF-INDUCTANCE OF 



TABLE IV. 



7. The only available means of testing the above methods of computing self- 

 inductances and of finding the limit outside which they are practically reliable is to 

 compare the results they give with those given by LOBENZ'S* exact elliptic integral 

 formula for the self-inductance of a current sheet solenoid, which is 



m 



3 d? ( F k 3 



where a is the radius, d the length of the solenoid, and 



. 

 1 



Thus consider the case of a solenoid whose length is twice its radius. 

 Here 



* ' WIED. Ann.,' 7, p. 161, 1879, 



