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RE: Variable Capacitance and Inductance
Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
Let me quote Tesla's own words from your original post, let
me point to the particular statements in them, and then let me
highlight the problems that I see with them (based on my own
observations and measurements - and I have detailed measurements in
my files which you will find in the list archives if you look back
> Exactly as mechanics and engineers have taken it for granted that the
> pliability of the spring remains the same, no matter how it be placed
> or used, so electricians and physicists have assumed that the
> electrostatic capacity of a conducting body, say of a metallic sphere,
> which is frequently used in experiments, remains a fixed and
> unalterable quantity, and many scientific results of the greatest
> importance are dependent on this assumption. Now, I have discovered
> that this capacity is not fixed and unalterable at all. On the
> contrary, it is susceptible to great changes, so that under certain
> conditions it may amount to many times its theoretical value, or may
> eventually be smaller.
First point: he is talking about a conductive body, in
particular a sphere. It could have been a car body. It matters not.
He is talking about *that* body and nothing else (wires and towers
included). I hope we are clear on that point.
> Continuing the investigation of this astonishing phenomenon I observed
> that the capacity varied with the elevation of the conducting surface
> above the ground, and I soon ascertained the law of this variation.
> The capacity increased as the conducting surface was elevated, in
> open space, from one-half to three-quarters of 1 per cent per foot of
> elevation. In buildings, however, or near large structures, this
> increase often amounted to 50 per cent per foot of elevation, and this
> alone will show to what extent many of the scientific experiments
> recorded in technical literature are erroneous.
He is now saying that the capacitance of the conductive body
increases with elevation. Although he doesn't say "isolated", that is
implied - he mentions no other conductor (e.g. pipe, wire etc.). He
is ascribing the property of increased capacitance with elevation to
the body alone.
BUT, he *cannot* discount anything connected to it which may
influence the readings he is getting, and he makes it clear in the
next quote that his readings are based on oscillation frequency.
> The importance of these observations will be better appreciated when
> it is stated that owing to these changes of a quantity supposed to be
> constant an electrical circuit does not vibrate at a uniform rate, but
> its rate is modified in accordance with the modifications of the
Note that last bit well.
Thus a circuit vibrates a little slower at an elevation than
> when at a lower level.
There is a problem here too. Included in my series of measurements
are some showing clearly that a *resonator* that is elevated shows a
*rise* in its frequency of oscillation. That is what I would expect
given that it has moved further away from the ground plane. i.e. -
its capacitance to ground has *dropped*. And so it should with the
sphere, should it not? Is that not reasonable? Please address this
question and show me exactly why my reasoning is in error.
If you would like the benefit of a number of days labour, I
would be happy to send you the files of measurements offlist to save
you time in hunting for them. I don't wish to bore the list with yet
On 23 May 2002, at 8:08, Tesla list wrote:
> Original poster: "David Thomson by way of Terry Fritz
> Hi Malcolm,
> >He doesn't always, and if there is any doubt about that I would be happy to
> bring his Guide in and quote the page in questiuon.
> I would prefer if you did use exact quotes. It makes it easier to carry on
> a focused discussion.
> >> Richard Hull notes these daily changes, too, as in his comment of Tesla's
> November 7 entry.
> >Yes. But he also noted that on one occasion at least, Tesla claimed some
> massive increase in capacitance with a relatively tiny increase in height
> (which he vehemently took issue with).
> Richard Hull is an accomplished Tesla coil researcher of his own good works.
> But I must offer my criticism of his book on Tesla's notes for his
> unqualified opinions regarding Tesla's measurements. Richard Hull does not
> offer data to back up his opinions; Tesla does. Until Richard actually
> takes measurements under the same conditions as Tesla, his baseless opinions
> cannot be used for scientific inquiry.
I for one do not believe that Richard came to these conclusions
without taking a lot of measurements.
> It reminds me of my ninth grade science teacher...
What reminds you of that? The fact that I'm asking questions? Suppose
we had blindly accepted theories that the resonator was a lumped
tuned circuit. Where would that have got us? Suppose we had accepted
theories that the resonator could be modelled as a uniform
transmission line. Where would that have got us? I amongst others
took issue with both those ideas and it was not an overnight whim to
prove the world wrong. It was based on a good deal of measurement and
observation. Many things I agreed with - some I simply could not.
We came to an experiment
> in our manual where a ping pong ball was placed in an upside down funnel and
> we had to blow into the funnel while releasing the ball. The teacher said
> there was no point in doing the experiment since it was obvious the ball
> would simply fall to the floor. Being of an inquisitive mind, I suggested
> we do the experiment anyway. The teacher rose his voice in arrogance and
> tried to make a mockery of me in front of the class and had me stand in
> front of everybody while I did the experiment. To his surprise, the ball
> stayed in the funnel due to eddy currents of air. And I was able to make a
> snide remark that made his face turn red.
I don't see the point of quoting this - unless you are seeking to
ascribe those same lamentable qualities to myself or others.
> We should all have questioning minds, but we must all have respect for
> others at the same time. If one of the brightest minds in human history
> said capacitance and inductance were variable, we had better prove him wrong
> with data and not blow his research away with uninformed opinions.
I did not and have not taken issue with variability of capacitance
(or inductance for that matter) when the experimental conditions (sun
atmosphere, height or whatever) are altered. What I am taking issue
with is the notion that elevating a conducting body *increases* its
capacitance. That is what Tesla said. I challenge you to explain why
such an increase should occur. Please address this point in your