Harris, Graalman, and Velocity Factors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Paul Nicholson" <paul-at-abelian.demon.co.uk> 

Does anyone know if Ed Harris and Mark Graalman are still
doing Tesla coil stuff?  Are they still on the list? - I guess
not.   There are a few of their posts in the list archives
from circa 1994-96, very well worth reading.  Some are as
relevant today as then.  For eg,

  http://www.pupman-dot-com/listarchives/1995/august/msg00020.html
  http://www.pupman-dot-com/listarchives/1995/august/msg00021.html

Oh, and this one too is a good one...

  http://www.pupman-dot-com/listarchives/1996/january/msg00096.html

Those guys knew what they were talking about and had the sort of
attitude that can't help but lead to progress... wish they were
still active on the list.

As you can probably tell, I've been trying to dig into the
history of awareness of the relationship between velocity
factor and h/d ratio, and the attitudes to wire length issues
in general.

We can compare the velocity factor coefficient (5/4)*(h/d)^(1/5)
given by Ed Harris in 1996 to a more recent formula,

  http://www.abelian.demon.co.uk/tmp/ph1h.gif

The '96 formula doesn't do too bad.  Eight years on we have a
good collection of accurately measured coils and also precision
numerical models, so the more recent formula has a better fit
(at least for h/d > 2 or thereabouts, we still lack data for
small h/d coils).

Does anyone know of anything pre 1994 that goes into this topic?
--
Paul Nicholson
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