Tesla found that high frequency currents were harmless when contacted by the human body. Discharges from these generators traversed the outer surface of materials, never penetrating matter with depth. There was no danger when working with high frequency currents. He also observed their very curious and beautiful spark effects. They hissed and fizzled all over wire conductors, could stimulate luminescence in low pressure gas bulbs, seemed to traverse insulative barriers with ease, and made little pinwheels spin like delicate little fireworks displays.

Though curious, the effects were weak and furtive. They seemed to intimate some future technology which he was yet unable to penetrate. Tesla learned that his intuitions and visions were infallible. What he guessed usually proved true.’ This very personal revelation, he later claimed, was his greatest discovery.

As the safety of all personnel was his main concern, he was consumed with the idea of making his High Frequency Polyphase System completely safe for human operators and consumers alike. An extensive examination of each System component was undertaken with this aim in mind. Tesla was thorough and relentless in his quest for safety and efficiency.

But, his involvement with alternating currents would come to an abrupt and unexpected end. During a series of experiments which followed these high frequency tests, an amazing seldom-mentioned accident occurred in which Tesla observed a phenomenon which forever altered his view of electricity and technology.


Tesla was an avid and professional experimenter throughout his life. His curiosity was of such an intense nature that he was able to plumb the mysteries of an electrical peculiarity with no regard for his own comfort. Whereas Edison would work and sleep for a few hours on the floor, Tesla would never sleep until he had achieved success in an experimental venture. This marathon could last for days. He was once observed to work through a seventy two hour period without fatigue. His technicians were in awe of him.

The Victorian Era was flooding over with new electrical discoveries by the day. Keeping up with the sheer volume of strange electrical discoveries and curiosities was a task which Tesla thoroughly enjoyed …and preferred. His Polyphase System in perfect working order, the pleasurable occupation of studying new gazettes and scientific journals often fascinated his mind to the exclusion of all other responsibilities. A millionaire and world heralded genius before the age of thirty, Tesla sought the pure kind of research he had so long craved.

Whenever he observed any intriguing electrical effect he immediately launched into experimental study with a hundred variations. Each study brought him such a wealth of new knowledge that, based on phenomena which he observed, he was immediately able to formulate new inventions and acquire new patents.

Tesla’s New York laboratories had several sections. This complex was arranged as a multi-level gallery, providing a complete research and production facility. Tesla fabricated several of his large transformers and generators in the lower floors, where the machine shops of this building were housed. The upper floors contained his private research laboratories. He had attracted a loyal staff of technicians. Of all these, Kolman Czito was a trusted friend who would stand by Tesla for the remainder of his life. Czito was the machine shop foreman in each of Tesla’s New York laboratories.

Tesla observed that instantaneous applications of either direct or alternating current to lines often caused explosive effects. While these had obvious practical applications in improvement and safety, Tesla was seized by certain peculiar aspects of the phenomenon. He had observed these powerful blasts when knife-switches were quickly closed and opened in his Polyphase System. Switch terminals were often blasted to pieces when the speed of the switchman matched the current phase.

Tesla assessed the situation very accurately. Suddenly applied currents will stress conductors both electrically and mechanically. When the speed of the switch-action is brief enough, and the power reaches a sufficiently high crescendo, the effects are not unlike a miniature lightning stroke. Electricity initially heats the wire, bringing it to vapor point. The continual application of current then blasts the wire apart by electrostatic repulsion. But was this mechanistic explanation responsible for every part of the phenomenon?

The most refractory metals were said to be vaporized by such electrical blasts. Others had used this phenomenon to generate tiny granular diamonds. Yes, there were other aspects about this violent impulse phenomenon which tantalized him. Sufficiently intrigued, he developed a small lightning “generator” consisting of a high voltage dynamo and small capacitor storage bank. His idea was to blast sections of wire with lightning-like currents. He wanted to observe the mechanically explosive effects which wires sustain under sudden high-powered electrifications.

Instantaneous applications of high current and high voltage could literally convert thin wires into vapor. Charged to high direct current potentials, his capacitors were allowed to discharge across a section of thin wire. Tesla configured his test apparatus to eliminate all possible current alternations. The application of a single switch contact would here produce a single, explosive electrical surge: a direct current impulse resembling lightning. At first Tesla hand-operated the system, manually snapping a heavy knife switch on and off. This became less favorable as the dynamo voltages were deliberately increased.

He quickly closed the large knife switch held in his gloved hand. Bang! The wire exploded. But as it did so, Tesla was stung by a pressure blast of needle-like penetrations. Closing the dynamo down, he rubbed his face, neck, arms, chest, and hands. The irritation was distinct. He thought while the dynamo whirred down to a slow spin. The blast was powerful. He must have been sprayed by hot metal droplets as small as smoke particles. Though he examined his person, he fortunately found no wounds. No evidence of the stinging blast which he so powerfully felt.

Placing a large glass plate between himself and the exploding wire, he performed the test again. Bang! The wire again turned to vapor…but the pressured stinging effect was still felt. But, what was this? How were these stinging effects able to penetrate the glass plate? Now he was not sure whether he was experiencing a pressure effect or an electrical one. The glass would have screened any mechanical shrapnel, but would not appreciably shield any electrical effects.