Tesla ? coil

From:  Terry Perdue [SMTP:terryp-at-halcyon-dot-com]
Sent:  Wednesday, June 03, 1998 7:31 PM
To:  Tesla List
Subject:  Re: Tesla ? coil

Raymond Koonce wrote:

> Some time ago I visited the Science Place museum at Dallas Fair Park and
> witnessed the "Electric Show".  There was a demonstration of a large VanDe
> Graf generator (very impressive) and a coil quite unlike a conventional
> Tesla coil.  It was a orizontally- mounted ~3 ft. diameter coil which
> tapered to a ~4" disk from which the discharge (6-8 feet long) emanated.
> The controller apparently had a rotary gap (completely enclosed).  The
> only connection from the controller to the coil was by two thick cables.
> Does anyone have an idea what type of coil this is?

I've only been subscribed to this list a short time, but this is the first
reference I've seen describing a tapered secondary. It reminded me of the TC
I saw as a kid at Griffith Observatory, outside LA, I believe. I recall it
as having a flat spiral primary of flat copper strap, and a tapered
secondary with a round terminal with spikes on opposite sides. It discharged
to the walls of the room, a few feet away. Does anyone know if there's an
advantage to tapering the secondary this way?