between them is like
the electrostatic field between two capacitor plates.
As he described it, an evacuated
bulb was place between the electrodes:
... when we excite luminosity in exhausted tubes...,
the effect is due to the rapidly alternating electrostatic potential;
... the medium is harmonically strained and released.5
He also noted:
It
might be thought that electrostatic effects are unsuited for such
action at a distance... It is true that electrostatic effects
diminish nearly with the cube of distance from the coil, whereas
electromagnetic inductive effects diminish simply
with distance. But when we establish an electrostatic field
of force, the condition is very different, for then, instead of
the differential effect of both the terminals, we get their conjoint effect.6
To make sure that the difference between the type of
fields he intended and those of Hertz was understood he explained:
As the term
electrostatic might imply a steady electric condition, it should
be
remarked,
that in these experiments the force is not constant, but varies...
When two conducting
bodies are insulated and electrified, we say that an electrostatic
force is acting between them.7
Tesla's emphasis on the non-Hertzian
nature of his signaling process, particularly when taken within
the context of his work with electrostatics, indicates the mode
of propagation involves similar electrostatic effects between
a transmitter and receiver. As he often insisted, this mode of
transmission differs significantly from that of Hertzian
waves in that this one is a form of conduction:
So far, I have
considered principally effects produced by a varying electrostatic
force
in an insulating medium, such as air. When such a force is acting
upon a
conducting
body of measurable dimensions, it causes within the same, or on
its
surface, displacements of the electricity, and gives
rise to electric currents.8
Also:
Some enthusiasts
have expressed their belief that telephony to any distance by
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induction
through the air is possible. I cannot stretch my imagination so
far, but I
do firmly believe
that it is practicable to disturb by means of powerful machines
the electrostatic condition of the earth and thus transmit
intelligible signals
and
perhaps power.9
Tesla believed that the earth was not just a sink into
which electrical energy can be poured, but that it is a reservoir
of charge. The capacity of the earth is determined by the standard
formula for the capacitance of an isolated sphere of radius R:
For the earth,
this works out to 708 microfarads.10
Tesla's idea
was that his high power transmitter he could cause the earth's
charge to oscillate and that these oscillations could be detected
anywhere on the globe. He further noted that these oscillations
were changes in pressure, "the energy will be economically
transmitted and very little power consumed so long as no work
was done in the receivers.11
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