The Turn Of The Century Electrotherapy Museum

6" Pancake Coil for producing Phantom Streamers
with Negative Leaders
(Negative Discharges issue from the ball terminal and terminate into Positive Phantom Streams)

Completed Coil, 500 turns of wire.  Hard rubber (Ebonite/Vulcanite) post, 3/4" Ball Terminal.  Primary windings are coming out of the side.
Outermost end of the secondary coil is grounded to one leg of the primary winding.  The innermost secondary winding is insulated with wax
within the hard rubber and terminates into the brass sphere.

Kinraide's 22" x 28" photos exhibited in the year 1900 of Positive (Filiciform) and Negative (Plumous) Electricity

The discharge from this coil resembles the thick white negative discharges shown here,
roughly 2" long, with 4" - 5" positive streams issuing from their tips.

In complete darkness, after the eyes have adjusted, minute amounts of power sent through the coil will produce a rich variety of sparks
such as those seen above.  The negative streams are roughly 1/4" - 3/8" thick at the terminal, extending out into positive streams with
branches from 1/16" - 1/8" thick or more.

Winding the coil...

91 Layers, Approx. 5 1/2 turns per layer - 6" diameter, 27 AWG wire with .015" thick interleave material.

The interleave material has a polyester / cellulose base; a pleated form of  media used in the manufacture of water filters.

A closeup scan of a similarly wound coil.

A smaller 4" variation of this coil.

While the Phantom Streams do not appear on the digital photos, below are some electrical discharges
observed in setting up the coil for the tests.  The phantom streams are actually surrounding all of this activity.

It is curious that when the ball is charged negative, a larger sphere terminal will act to add capacity to the spark without
detuning the coil from resonance.  Sparks were taken still from the coil when the 3/4" brass ball was replaced with
a 6" copper sphere.  Normally the system would require tuning after this.

This work is inspired by Thomas Burton Kinraide's Photographs of Electrical Phenomena from the 1890s.

I built a reproduction of his machine (above), and look after nearly 500 of his 11 x 14", 8 x 10", and 7 x 9" Glass Plate Negatives.

The intricate blur of details from a 1 second photo, 10" discharge at low power.
  When the phantom streams are produced, they extend outward in all directions of space from all metallic parts of the terminals
a distance of a foot or more.