Most researchers and engineers are fixed in their view of Nikola Tesla and his discoveries. They seem curiously rigidified in the thought that his only realm of experimental developments lay in alternating current electricity. This is an erroneous conception which careful patent study reveals. Few recognize the documented facts that, after his work with alternating currents was completed, Tesla switched over completely to the study of impulse currents. His patents from this period to the end of his career are filled with the terminology equated with electrical impulses alone.

The secret lay principally in the direct current application in a small time interval. Tesla studied this time increment, believing that it might be possible to eliminate the pain field by shortening the length of time during which the switch contact is made. In a daring series of experiments, he developed rapid mechanical rotary switches which handled very high direct voltage potentials. Each contact lasted an average of one ten-thousandth second.

Exposing himself to such impulses of very low power, he discovered to his joy and amazement that the pain field was nearly absent. In its place was a strange pressure effect which could be felt right through the copper barriers. Increasing the power levels of this device produced no pain increase, but did produce an intriguing increased pressure field. The result of simple interrupted high voltage DC, the phenomenon was never before reported except by witnesses of close lightning strokes. This was erroneously attributed however to pressure effects in air.

Not able to properly comprehend their nature at first, Tesla also conservatively approached the pressure phenomenon as due to air pressure. He had first stated that the pressure field effect was due to sharp soundwaves which proceeded outward from the suddenly charged line. In fact, he reported this in a little-known publication where he first announced the discovery. Calling the pressure effects “electrified soundwaves”, he described their penetrating nature in acoustic terms.

Further experimentation however, gradually brought the new awareness that both the observed pressure effect and electrical shock fields were not taking place in air at all. He demonstrated that these actions could take place in oil immersions. Impulse charged lines were placed in mineral oil and carefully watched. Strong pressure projections emerged from sharp wire ends in the oil, as if air were streaming out under high pressure.

Tesla fast believed that this stream was wire-absorbed air driven off by electrical pressure. Continual operation of the phenomenon convinced him that the projected stream was not air at all. Furthermore, he was not at a loss to explain the effect, but was reluctant to mention his own theory of what had been generated by high voltage direct current impulses.

Tesla made electrical measurements of this projective stream. One lead of a galvanometer was connected to a copper plate, the other grounded. When impulses were applied to wire line, the unattached and distant meter registered a continual direct current. Current through space without wires! Now here was something which impulses achieved, never observed with alternating currents of any frequency.

Analysis of this situation proved that electrical energy or electrically productive energies were being projected from the impulse device as rays, not waves. Tesla was amazed to find these rays absolutely longitudinal in their action through space, describing them in a patent as “light-like rays”. These observations conformed with theoretical expectations described in 1854 by Kelvin.

In another article Tesla calls them “dark-rays”, and “rays which are more light-like in character”. The rays neither diminished with the inverse square of the distance nor the inverse of the distance from their source. They seemed to stretch out in a progressive shock-shell to great distances without any apparent loss.


Nikola Tesla now required greater power levels than those provided by his mechanical rotary switch system. He also saw the need for controlling ultra-rapid current interruptions of high repetition (“succession”) rates. No mechanical switch could perform in this manner. He had to envision and devise some new means by which ultra-rapid interruptions could be obtained. In his best and most efficient system, highly charged capacitors were allowed to impulsively discharge across special heavy duty magnetic arcs.

The magnetic arc gap was capable of handling the large currents required by Tesla. In achieving powerful, sudden impulses of one polarity, these were the most durable. Horn shaped electrodes were positioned with a powerful permanent magnetic field. Placed at right angles to the arc itself, the currents which suddenly formed in this magnetic space were accelerated along the horns until they were extinguished. Rapidly extinguished!

Arcs were thus completely extinguished within a specified time increment Tesla configured the circuit parameters so as to prevent capacitor alternations from occurring through the arc space. Each arc discharge represented a pure unidirectional impulse of very great power. No “contaminating current reversals” were possible or permissible.

Reversals.. alternations.. would ruin the “shock broadcast”. The effect was never observed when alternating currents were engaged. High voltage was supplied by a large dynamo. Tesla could speed or slow this dynamo with a hand operated rheostat. Power was applied in parallel across the capacitor. The magnetic arc was linked almost directly to one side of this capacitor, a long and thick copper strap connecting the magnetic arc and the far capacitor plate.

This simple asymmetric positioning of the magnetic arc discharger to one side of the dynamo supply produced pure unidirectional electropositive or electronegative impulses as desired. Tesla designed this very simple and powerfully effective automatic switching system for achieving ultra-rapid impulses of a single polarity. Capacitor values, arc distances, magnetic fields and dynamo voltages were all balanced and adjusted to yield a repetitive train of ultrashort singular impulses without “flyback” effects.

The system is not really well understood by engineers, the exceptional activities of the arc plasma introducing numerous additional features to the overall system. While the effects which Tesla claimed can be reproduced with electron tube impulse circuitry, these produce decidedly inferior effects. The overall power of the basic arc discharge is difficult to equal. Tesla eventually enclosed the magnetic arc, immersing the gap space in mineral oil. This blocked premature arcing, while very greatly increasing the system output.