201, 202] DIELECTRICS AND MAGNETIZABLE BODIES. 391 



induction given by Maxwell. It is solenoidal in intrinsically 

 magnetized bodies as well as elsewhere. The induction, g, which 

 is divergent in intrinsically magnetized bodies, and which is 

 defined as pF, we shall call the Hertzian induction, and denote by 

 % H . In magnetically soft bodies these two inductions are identical, 

 but in intrinsically polarized bodies they differ. 



If we write equation (3) as 

 (6) 



and from it subtract 

 (5) 

 we have 



(7) div ( g H - F) = 4-7T div (7 - J ). 



Now if we call /$ the induced polarization, we have as always 



(8) Ii = KF Jj^l Fi /=/+/,. 



Inserting these in (7) 



div (g H - F) = 4vr div I, = div {(ft, - 1) F}, 

 and transposing div F, 



(9) divg*=divO*F), 

 agreeing with the definition of g H . 



202. Heaviside's treatment of Intrinsic Polarization. 



The treatment given by Heaviside differs in several respects from 

 that just given. According to that author the induction is always 

 solenoidal, so that true magnetic charges do not exist. The only 

 reason given for this assumption seems to the present writer 

 insufficient, being, as stated by Heaviside, "to exclude unipolar 

 magnets." It appears that the exclusion of unipolar magnets 

 merely means that for any magnet the integral charge is zero, 



which simply means that the distribution is what we have called 

 polarization, and lays no restriction on the divergence of the 

 polarization or induction. It might be supposed that Heaviside's 

 induction was what is here called the Maxwellian induction, were 

 it not for the fact that he says that " we use always " g = fiF, In 



