Its main proponent, and inventor, Wilbert Brockhouse Smith developed this coil sometime during the 1950's (Smith died in 1961).
Originally, Dr. Smith was involved in the top-secret program "Project Magnet". This project, allegedly, was a government-sponsored program to produce an aircraft which operated on the same propulsion/flight principles of U.F.O.'s. "Officially", at some point, the program was terminated. At some point, concurrently, Smith was tinkering around with new styles of coil windings. It was during this period of time when he developed the caduceus coil.

The coil is said to produce electromagnetic waves which travel parallel to the coil windings. This violates electromagnetic convention as the standard rule for creating electromagnetism is that the waves are produced perpendicularly (with respect to the coil windings).
Also, supposedly, a caduceus coil transmits these electromagnetic waves at super-luminal velocities (i.e., at faster-than-light speeds).
It is interesting to note that, last year, a Canadian scientist was credited with sending a radio broadcast using "radio-like waves" which were travelling faster than the speed of light.

Smith claimed that timepieces, which were within the caduceus coil's region of greatest magnetic field flux density, measured time at a different "rate and direction of time flow" than other timepieces which were outside of the coil's magnetic field influence.
The caduceus/tensor coil (with proper frequency/voltage) supposedly creates scalar electromagnetic waves that travel at super-luminal velocities (i.e., faster-than-light speeds).

As an electronics engineer, there is one thing that comes to mind regarding this. When an electromagnetic field is created, any thing within the densest portion of that field tends to take on the same potential, polarity, frequency, and velocity of that field. This applies both to life forms and inanimate objects.

Some people refer to an objects, or life forms, energy as its "aura", electromagnetic field, or Kirlian field. In fact, there is a seldom known, little used, formula known as the "Johnson Effect" which can be used to ascertain the power levels of an objects, or life forms, electromagnetic field. The reason it was discarded is because it leans towards inaccuracy at frequencies above the Earth's magnetic field frequency (about 7.8 Hz).
With respect to what I've mentioned, I believe Einstein's theory of relativity states that if an electromagnetic wave were to (somehow) be propagated at velocities beyond the speed of light, then that wave would move backward in time.

Or, more specifically stated, that the Universe's "time" would start going backward relative to the "time" experineced by the wave (which, if a wave could have consciousness, would experience a normal, forward, progressive "time").
I believe this is what happened to my friend when he was operating his machine. By the way, he was wearing a digital watch when this happened (the first time). However, the static charge he experineced blew the digital timer circuitry inside the watch.
What is really bizarre is I read a story out of the "Weekly World News" (OF ALL PLACES!) that stated the U.S. government was involved in a project called the Temporal Transmission Research Project. The story stated that they place an object inside a hollow aluminum tube and then subject the tube to a high- frequency electromagnetic field that travels faster than light.
In this fashion, supposedly, the tube (and internal contents) are supposed to be able to travel into the past. We all know that aluminum is a great conductor of electricity.

The interesting analogy between that story, and my friend's experience, is that his coils were hollow, were producing extremely high frequencies, and (I believe) were functioning as a caduceus (or tensor) coil.

The W.W.N. story also stated that a government scientist had volunteered to go back to the year 1918, remain for 25 minutes of subjective time, then return. They go on to say that he went, but never returned.

Continuing, they said that the project members then decided to look over old publicatations (from 1918) looking for clues as to what happened. After about two months of searching, they contend, they found an old microfiche copy of a now-defunct police journal which had a very strange article in it.
In the article, it shows what appears to be (in a picture) a metal tube about two feet long and containing the crushed remains of a man. Also, in the picture, is what looks like a cellular phone (lying on the ground) about one to two feet away.
There was a caption below the picture, but I vageuly remember what it said (I was more interested in the picture).
The reason I was so interested in the picture is because of something I noticed about it. I've been working in darkrooms, and with cameras, for more than 30 years and what I saw blew me away.

The picture was taken at night and shows the tube, the "cellular phone" (if that's what it was-suppose it was a "recall device" to allow the man to get back to his own time?), some police officers (in old-style uniforms), some old style police cars, and (in the background) a row of spectators.

The thing that aroused my interest in the picture is that these spectators looked as if they were a good 60 - 80 feet from the camera. You see, the modern electronic flash (even the ones with the biggest xenon flash lamps) can't illuminate (in darkness) more than about 40 - 45 feet at the MAXIMUM.

In the old days, the "press 25" flash bulbs (on the other hand) were able to illuminate (in darkness) well up to 80 - 85 feet or so.
So, it is my contention that MOST of the picture is genuine (that is, taken in 1918). I don't know about the tube and the "cellular phone" though. I can tell you, though, if the picture is a composite (the tube and "cellular phone" being "pasted" into the picture), whoever did it was a master of "special effects/trick photography".

I don't know if the Weekly World News would have THAT kind of money as those type of imagery artists are damned expensive to hire. Also, in the picture, I noticed several blades of grass that appeared IN FRONT OF not only the "cellular phone", but the metal tube as well.
I believe my friend's coils were functioning as a caduceus.
Vanguard Sciences/KeelyNet comments
Some might snicker at quoting the Weekly World News as a source, however, every now and then the tabloids will mention something interesting that can be checked. I know, because about 4 years ago, a few paragraphs were printed in the Globe newspaper about a fellow who had figured out how to make things invisible.
I called the Globe and asked for the fellows name and address. They refused to provide verbally but said their policy for followup requests must be made by mail. So, I sent them a letter with the story name, the page and issue.
Within about a week, I received the name of the inventor, his phone number and address. I called and we spoke for a couple of hours. Fascinating theory that he got from Star Treks' Cloaking Device.
He pursued it and now has a company listed on the web.