The Turn Of The Century
Electrotherapy Museum
Kinraide Coils Article

Kinraide Coil for Direct Currents

Kinraide Coil for Alternating Currents

Kinraide Coil for Alternating Currents (Improved Design)

Discharge from Kinraide Coil on Photographic Plate

Wiring Diagram from Strong's High Frequency Currents

Swett & Lewis:  The Kinraide Coil

Closeup Photo of Kinraide Coil (Direct Current version) from Swett & Lewis Catalog.

Swett & Lewis:  The Jackson Coil


First page to Kinraide Coil Patent

The name Thomas Burton Kinraide is practically unknown, yet his work remains among my personal favourites.

While Nikola Tesla can be considered the first person to experiment with Röntgen Rays and X-Ray Tubes using
high frequency currents, Thomas Burton Kinraide was certainly the man who perfected these ideas for the
medical field.  Kinraide started this research in 1896.

[At this time, the only High Frequency coil mass-produced  was "The Knott Apparatus" in 1897.  This
was the first commercial Tesla Coil, and it was  made expressly for X-Ray use.]

According to Frederick Finch Strong (who became acquainted with with Kinraide at his Jamaica Plain
Laboratory), Kinraide demonstrated X-Rays powerful enough to view bones of the trunk as clearly as those
of the hand.  His method was to discharge a large bank of storage cells through a platinum break and 8"
Ruhmkorff Coil.  The induction coil was provided with a discharging circuit consisting of a kerosene-immersed
plate capacitor connected in series with an oil-immersed Tesla Coil by a heavy spark gap.  Kinraide later
perfected this bulky apparatus with the Kinraide Coil seen in the patent and plates above.  Frederick Finch
Strong (who was at the time Professor of Anatomy at Boston University School Of Medicine) began his famous
studies of the therapeutic effects of high frequency currents.  (Strong was later an instructor in Electrotherapeutics,
he is credited for having invented the well-known vacuum electrode, and for having written one of the best
books on High Frequency Currents).

Both Kinraide and Strong created a series of prototypes from 1896-1901.  Kinraide continued to improve his
design, and Strong supervised the work of Mr. Earl L Ovington (of the Massachusetts Institute of Technology)
to create his own high frequency apparatus "The Strong-Ovington Static Induction And High Frequency
Apparatus".   The "Strong-Ovington" apparatus was officially marketed in 1902.  Improvements
in the years followed, and Strong developed larger ornate versions called The Ajax Coil, The Ajax Special,
and finally The Hercules Coil.

After Strong made several publications concerning the therapeutic use of high frequency currents, many people
tried to use Kinraide Coils therapeutically - but the currents were far too heavy to be used with success for this
purpose.   Similarly the Strong-Ovington Apparatus was found unsuitable for the production of X-Rays. 

A Boston company Swett & Lewis began manufacturing  Kinraide Coils in 1901 under the supervision of
Mr. Howard Jackson.  The original Kinraide Coils were notorious over time for having problems with their spark
gaps.  These problems were somewhat overcome by the modifications of Swett & Lewis. 

Under the supervision of T. B. Kinraide, Mr. Howard Jackson developed a similar device made expressly for
therapeutics, "The Jackson Coil".   

As can be seen from the description above, High Frequency Currents developed simultaneously yet independently
by various individuals.  While L E Knott Apparatus Company had the first commercial Tesla Coil for X-Ray use,
I feel this device was a bit inferior to Kinraide's designs with regard to efficiency and power.

My first experiments with "Kinraide Coils" were with an apparatus I donated to NTM in Prague, Czech Republic,
"The Prague Coil".  Seen below is a photo of an early form of this device:

Similar to Kinraide, my early devices consumed a lot of power and yielded an enormous output.  The discharge
of the two 9" Diameter x 2" Tall coils is over 16". 

I later tried to build a simpler and more compact version of the "Kinraide Coil", one which could be adapted both
for Therapeutic and X-Ray work.  The result of the prototype is the device seen in the photos below, the
"Behary-Kinraide-Jackson Coil".  This device consumes from 100-200 watts, and produces voltages high enough
to power a large X-Ray tube (such as the 18" Victor High Frequency Tube seen below) or to safely take to the
human body.

Behary-Kinraide-Jackson Coil

Large 18" Victor High Frequency X-Ray Tube!

Sparks between wires suspended from terminals.

Effluves are safe enough to take directly to the human body.

(C) Jeff Behary, 2004