# Re: Variable Capacitance and Inductance

```Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
>
> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
>
> Hi Ed,
>
> >His statement"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."
> simply doesn't fit what we actually see and measure.
>
> It would be an insult to Tesla to assume he didn't know that raising a
> copper ball would increase capacity after he spent a month doing just that
> at Colorado Springs.  He must be taking the capacitance due to distance into
> account and referring to the variation from expected values.  For example,
> he probably measured the capacitance horizontally and then vertically and
> received a 50% difference between the two.  It would be an interesting
> experiment.
>
> Dave

Sorry, no way!  If the quote is correct the man was just plain
antennas calculate the capacitance of the top structure (sometimes
pretty complicated, requiring finite element analysis techniques) and
the measured values agree with the predicted ones within the accuracy of
the input parameters.  In effect, the experiment has already been run
hundreds or thousands of times and the answers all agree with theory.
Not quite sure what you mean by "he probably measured the capacitance
horizontally and then vertically and received a 50% difference between
the two". Do you mean that the lead to his sphere was horizontal for one
measurement (everything close to the ground) and that it was
perpendicular for the other?  IF the capacitance he was referring to was
that of the lead PLUS the sphere, when the lead was horizontal the
capacitance would have been substantially higher, assuming that the
"bottom" end was always at the same height above ground.  Something
badly wrong here!  If you had a sky hook you could run the experiment in
a few minutes.........

Ed

```