144 Mr Glazebrook, On the general equations [April 28, 



, &i d/3 . d 2 ® 



and -,- =- = 4nru — ^ — T . 



ay dz dxdt 



They become identical with Maxwell's equations on putting 



We will consider further this case in which <I> is not zero. 

 Let ^ be the potential at any point arising from electrostatic 

 forces O that which arises from the polarization of the dielectric. 

 Then the equations in addition to (10) and (11) which we have 

 to consider are 



u =f, etc. 



" 7r ^" V dec doc ~dt) ' '" 



etc 



Differentiate (12) with reference to x, y, z in order, and add. 

 Then differentiating with respect to t, ' 



- K i{^+^ d i) w- 



From (10) and (12) we find 



d 2 ® 8 „ dJ rr d (d$t dn dF\ ,_.. 



^d^r^ F+ dx = - flK dt{d, + d^ + ^t) (14) > 



etc 



and by the usual transformation 



d 2 a 

 ^^2=V 2 a (15), 



and from hence by aid of the equations, 



dy dz dxdt 



etc. 

 we obtain 



rrd 2 ( 1 d®\ 2 /, 1 d®\ ni% . 



etc. 



Thus the magnetic force or, ft, 7, and the vector whose components 

 are /— t~ ~T~ > etc -> both travel with velocity 1/*J(/jlK). 



