Atoms with Properties of Polonium or Radium. 529 
§ 6. Alter fig. 1 slightly to make the two circles touch 
one another with the centre of the electrion, e, at the point 
of contact. The electrion still experiences equal attractions 
leftwards and rightwards and is therefore in equilibrium. 
Fig. 1,—Polonium. 
Fig, 2.—For 8 rays of Radium. 
Each atom experiences repulsion from its neighbour, which, 
: ; 4e.4e 4 
if r denotes the radius of the atom, is equal to - 2 ‘= 73 
; : Ae, 4¢? 
and attraction by the electrion equal to == = These 
forces being equal, each atom is in equilibrium. But the 
equilibrium is unstable: to prove this; separate one atom by 
a slight distance from the other, leaving the electrion in the 
other, free to move while the two atoms are held fixed. 
The electrion will be left vibrating, through a small range, 
wholly within the last-mentioned atom ; and, by sending out 
waves through ether, will come to rest at a small distance 
Phil. Mag. 8. 6. Vol. 8. No. 46. Oct. 1904. 20 
