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Answers

Greetings :

Joe Duszynski asks "Whats the inductance of a spherical inductor"

L = (2*PI)/9  * mu0 * a * n^2

where mu0 is the free space permeability, a is the radius of sphere, and n
is turns.

Now, perhaps you can tell me why you need this? These coils have some
interesting
properties; for one, the H field inside has !no! curl. Weird, huh? And
before the
flames start, nothing in Maxwells equation prevents this. The field is still
a dipole.
Just the inside behaves this way.

Timothy A. Chandler asks "How do I find the inductance of a Tesla coil"

This question has no answer. In fact, what you want to find is the self resonant
frequency of the coil. This includes the distributed capacity of the windings.
Forget about lumped L, these puppies are slow wave helical resonators. That was
Tesla's discovery, as far as I am aware. Towards this end I suggest you read
"Wide frequency range tuned helical antennas" by Sichak & Kandoian, Electrical
Communication, Dec 1953. Also can be found in Convention Record of the IRE, 1953
national convention. More recently, the Corum brothers have popularized this
idea,
check the old ITS proceedings for a good article on this. 

But more to the point, the only scientists who complain about 5% accuracy
are the
ones who never build things. Save the labor for when it counts, your time is
far more valuable. If you are really interested in make exact coils, check out
Grovers "Inductance Calculations; working formulas and tables" which will allow
you to make very accurate calculations of lumped L. These formulas take into 
account insulation thickness as well as form factor of coil. Suffice it to say,
I can't scan in the book for you. Try a !big! university library, they might
have
it. My copy is a Dover edition, perhaps they still print it?

Now for a question of my own; does anyone know a good discount house for
Tek, HP,
B&K test equiptment? 

K.

knagel-at-cnct-dot-com