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PHYSICS: H. BAT EM AN 
was built up from four of our elementary fields. It is important to notice in 
this connection that the volume density of electricity and electric current 
in an elementary field are independent of the direction in which the concen- 
trated charges move; this simplifies matters when we want to ascertain the 
structure of the aether for an electric pole that is built up in a specified way. 
When a number of radiant fields are superposed a cancelling of concentrated 
electric charges seems to be necessary in order that the principle of the con- 
servation of energy may hold and in order that steady states of motion may be 
possible. Even if the cancelling is not complete everywhere it must at least 
be sufficient to prevent any free electricity from going to infinity. If this 
less stringent condition is adopted it is possible to admit fields in which the 
charge associated with an electric pole fluctuates slightly and electric charges 
are fired from one electric pole to another. It may be possible to explain 
gravitation in this way for it will soon be realised that the necessary fluctua- 
tion of charge is exceedingly small. The question may also be raised whether 
it is necessary for there to be a complete cancelling of the charges in the ele- 
mentary aethers when a number of elementary fields are superposed. If the 
answer is in the negative the volume densities of electricity and convection 
current will be derivable from a function which satisfies the wave-equation 
at points not occupied by matter. 
Summing up the essential features of the present theory, we may say that 
all electric charges are supposed to really travel along rectilinear paths with 
the velocity of light; this implies that when electricity appears to move with a 
smaller velocity it is made up of different entities at different times being 
constantly renewed so to speak. The fact that an electric charge which has 
been moving along a rectilinear path with the velocity of light has no sur- 
rounding field 2 is quite consistent with the present view, for all electric charge 
arises from electric separation 3 and its aether is created in the process, conse- 
quently an electric charge which has moved along a rectilinear path for all 
time with the velocity of light would have no aether to support a field. 
When we admit the mathematical possibility that the electric charges in 
the universe have not existed in the free state for the whole of time we find 
that it is by no means certain that the aether fills the whole of space and this 
raises some interesting philosophical questions. Some of the logical diffi- 
culties 4 in the ideas of contact action and action at a distance are avoided 
in the present theory because an electric charge at a point P produces an 
effect at a distance point Q for the simple reason that either a portion of the 
charge itself, or a portion of the compensating charge that was created at the 
same time, actually goes to Q and helps to produce the particle that is acted 
upon, or rather the entity that represents the particle at the moment under 
consideration. 
Passing on to a brief consideration of some more familiar types of fields 
we shall superpose the fields of point charges using Lienard's potentials 
