298 



From either of these formulas we find 



6—1 s, — l 



= q 



« + 2 



^ + 2 — 



2pó^ 



(2") 



3 + 2d 



This formula is analogous to (J") in {a) and shows that to within 

 the first power of é the force on a sphere having spherical holes in 

 it is the same as if the sphere were moulded into a smaller sphere 

 without holes. Thus the conclusions drawn in (a) for the correction factor 



remain valid in this case. 



1 + 



Aiji ad 



(c) Lamindry structure of powder the directions of the laminae 

 being distributed statistically. (See fig. J). 



Fig. 1. 



ÏÏ 



The electric intensity may be resolved into two components 

 normal and parallel to the laminae respectively. 



(I) Normal component. 



Letting E^, E„ h^, A,, s^, f, be respectively the normal components 

 of the field intensity, the thicknesses, and the dielectric constants 

 of the interspaces between the laminae and the laminae themselves 

 we have: 



E^ E^ A, E^ -\- A, E^ 



Writing 

 and letting 



-' ^"' A,6,-i + A,e-i' 

 K E, +KE, = {h, + h,) Ë 



