Twin coil idea / Tesla's Lectures w/ coil specs: Feb 1892

Malcom and others,

Please note in Tesla's lecture in London Feb 1892 "High Frequency and High 
Potential Currents", (page 217 "Inventions, Researches, and Writings of 
Nikola Tesla" Barnes & Noble)

He mentions a small twin coil to produce extremely powerful fine-grain 
effluve without large sparks, to be demonstrated by one small and one large 
ring of wire in the same plane with ionisation inbetween.
Wound on thick Bohemian glass tube,  5cm diameter x 20 cm long.  Secondary 
is 24 AWG.
Primary is 12 AWG, and fits INSIDE of the secondary.
Two of these coils are used, with secondaries in series and primaries in 
multiple arc.  Condensers in series, spark gap in parallel.  Tubes placed in 
oil insulation 10-15cm apart.
Coil excited from 2 four-pint jars in series.

Tesla's lectures usually dwelled on various induction-type coils, and 
"Rochefort type resonators" coils where there are two series primaries and 
two multi-layer secondaries of small widths and large diameters.  Has anyone 
built these types of coils??

The metal rings in this lecture were 80cm and 30cm.  This same coil is said 
to have made a "strong luminous sheets" occupying a square meter.

I have built somewhat-similar single primary-secondary Violet Ray type 
disruptive discharge coils, multi-layered, many layers (~20) of relatively 
few turns (.25-5") but heavily insulated on either end to prevent 
sparkovers. (3" wide paper). I replaced the parallel-wire primaries of the 
originals with a 1/2" brass strap flat spiral, wound like tape on itself 
(insulated by paper) and get better results than the former method adopted 
by most manufacturers, taking up slightly more space.

Also twin coils Fig 132 page 207.  Clear drawings, and very interesting, 
with a ratio of primary:secondary 1:5.4 or 1:2.7 depending on whether 
primaries are series/parallel.

These coils would be intensely interesting to build, has anyone on the list 
attempted them??

I don't hear too much about these lectures on the list, and they mention 
many of our recent conversations on x-rays/ vacuum discharges/ funny 
streamers and sparks /etc.


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