1918-19.] An Electron-Transference Hypothesis, etc. 213 
Eliminating C and H from equations 1*16, 1*17, 1*18, we have 
1-19 
1+2P, d 2 F 
= curl H 
1 - P s dt 2 
= - curl (curl F) 
= A 2 F - grad (div F) 
= A 2 F 
since div F = 0 in free aether. 
If, however, /x is the refractive index of the medium, the equation of 
propagation is that of Maxwell, viz. 
1*20 
1-21 
1-22 
/x 2 F = A 2 F. 
1+2P, 
P - 
P* = 
’ glving 
/x 2 -l 
/* + 
[The work given in this section (b) so far is a vectorial modification of 
that given in Sir J. J. Thomson’s paper in Phil. Mag., 1906.] 
1-23 
Specific refractive index = 
yU , 2 — 1 1 
2 * D 
= R< 
IX- 
where D is the density of medium considered. 
If N 0 = number of atoms in 1 grm.-molecule of substance, 
i- = mass in grms. of 1 molecule. 
N 
1*24 
1*25 
1-26 
N, 
= I) = mass of 1 c.c. of substance. 
R S =^N 0 
{g (mE+Me)+? g} 
A s = atomic refractive index. 
A -r w ? 0 {Fl (mE+Me)+ 5} 
= WR S where W is atomic weight of substance. 
When s = 0, we obtain the case considered by Sir J. J. Thomson in his 
paper in Phil. Mag., 1906, viz. 
A [ E(mE + Me) 'j 
1-27 
R o = ^- 7rN o^ 4 
3 u 7rp(Me + ?wE) - Mmj9 2 j 
(c) Before we can proceed further, we must consider the magnitude 
