Morton on Electricity in Medicine

ALTERNATING CURRENTS OF HIGH POTENTIAL AND HIGH FREQUENCY, VIZ.: TESLA'S APPARATUS AND CURRENTS. "RAPIDLY ALTERNATING ELECTROSTATIC STRESSES."

It is characteristic of alternating currents, that their energy is manifested, not so much in the wire, as in the space surrounding it, and the greater the frequency and the potential, the more extensive do some of the phenomena outside of the wire become. In this space, energized by the alternating current traversing the wire, may be exhibited by the aid of proper devices arranged to capture and transform the electric energy, light, heat, mechanical motion and chemical action; lamps glow, metals fuse, motors are caused to spin, and chemicals to combine. And this space around the current conveying wire is not narrowed to minute fractions of an inch, but may be measured in yards. Here is a field of force within whose influence a patient may be readily brought. Such a field would be termed an alternating electrostatic field; it is most marked around the terminals of a secondary coil whose primary is conveying an alternating current. It is the same field as that associated with the spark discharges of electrostatic machines, and even in a lesser degree with our best constructed medical induction coils, as I have shown by glow lamp tests applied to them.

The electrostatic field was indeed familiar to all; but in a feeble and minor degree. In medicine it has been a prominent feature of administrations from the influence machine in both simple insulation of the patient, in the spark, and more particularly in my own method of the static induced or interrupted current, and has been in medical use in connection with that machine. But so far as relates to induction coils, little or no account has been taken of the electrostatic properties of the current. Our attention has been wholly occupied, as has been that of the electrical engineers, with the current in the wire, and not with properties of this current — the electrostatic field outside of it.

But in induction coils affording high frequency, high potential currents, for instance, from hand to hand, it must now be noted that we have to deal with two effects — 1st. The effect of the direct passage of the current through the body, and: 2nd, the lateral, surging, wave impulses spreading out in every direction from the passing current. The former of these effects alone has hitherto claimed attention. That the latter effects now claim attention alike in the industries and in medicine is due to the wonderful experiments of Nikola Tesla. We have, as he modestly says, the same apparatus, the induction coil, and the same phenomena, only the apparatus is operated differently, and the phenomena are presented in a different aspect. So different indeed is the aspect of the phenomena that the entire scientific world hails their presentation as a revelation.

Mr. Tesla's first publication was in the Electrical World, of Feb. 21, 1891, under the title of "Phenomena of Alternating Currents of very High Frequency." Referring to effects upon the human body he writes, "the discharge of even a very large coil cannot produce seriously injurious effects, whereas, if the same coil were operated with a current of lower frequency, though the E. M. F. would be much smaller, the discharge would be most certainly injurious." The writer's experiences tend to show that the higher the frequency the greater the amount of electrical energy which may be passed through the body without serious discomfort."

The Tesla Apparatus. — Mr. Tesla obtains the high frequency mechanically, and by the aid of a well known natural phenomenon — mechanically by a specially constructed dynamo machine giving a frequency of about 10,000 per second, and naturally, by aid of the intensely rapid alternating or oscillating discharge of Leyden jars or condensers. The latter carry the frequency up to anywhere from 500,000 to 1,500,000 alternations per second. Low frequency may, however, be employed when the condensers are in the secondary circuit.

How important an element the Leyden jar may be in increasing frequency both in the electrostatic phenomena of the influence machine already in medical use, and in the Tesla apparatus, may be judged of from a calculation of Dr. Oliver J. Lodge that a common pint Leyden jar discharged through an ordinary discharging rod will possess a rate of oscillation equal to about ten million per second.

Mr. Tesla's high potential is due to the frequency and to "step up" transformation by coils. It consists practically of a high frequency dynamo whose current enters a primary wire, a secondary wire within whose circuit is included a condenser and discharging rods, and again a coil to which a part of the secondary wire acts as a primary.

The Tesla effects, as they are now frequently termed, are obtained:

a. By direct connection with both terminals.

b. In the space intervening between the terminals, or in the space about either one singly.

Using the apparatus above described with alternating current dynamos of low or high frequency, Tesla obtains remarkable effects. Among them may be noted:

a. The brush discharge.

With two cotton covered wires_arranged parallel and near to one another, the wires are strongly illuminated by streams of flame, spreading from one to the other. The brush led from a circle of wire, 30. centimetres in diameter, to a small brass sphere, is formed into a beautiful cone of light, or again, concentrated upon small, thin wires, greatly intensifies the light.

With two circles of wire, respectively 30 and 50 centimetres in diameter, a continuous circular luminous sheet is produced.

An increase of the molecular or atomic vibration changes the color of the discharges from purplish to white.

In these experiments, the molecules of air about the terminals are intensely agitated, and give rise to the light.

b. Rotation of a motor connected to one terminal wire only of the coil.

c. Illumination of exhausted bulbs or lamps containing a refractory substance sealed within them, and when attached only to one terminal of the coil, the molecular bombardment within the bulb incandescenses the refractory substance, and emits light. Such substances are fused, disintegrated and dissipated by the intense electric bombardment.

Buttons of carbon, diamond, pumice-stone and carborundum were used. To protect the leading-in wire from the effects of the bombardment, a screen aluminium tube may be used, which acts electrostatically by reason of its conductivity, and also mechanically; the screen, becoming charged, economizes the energy supplied to the bulb by not taking it up after it is once charged. Again, the same exhausted bulbs are illuminated with- out the aid of a leading-in wire, the energy required being transmitted through the glass.

d. To excite vacuum tubes throughout the whole extent of a room, lighting up the tube wherever it is held in space, and at a distance from the conductor, the intense electrostatic field is set up by converting the oscillatory current of a condenser to a higher potential. Such a field Mr. Tesla establishes between two sheets of metal several yards in area and several yards apart. A vacuum tube held within the space between the metal sheets, glows intensely.

It becomes an interesting question to determine to what extent high potential, high frequency currents may be of value in medicine. The shock from the secondary coils above described are very light and can be taken without inconvenience. This to many has seemed remarkable on account of the very high voltage.. Much speculation has been indulged in as to why these currents do not produce great muscular contraction, and great pain, and dangerous results. It has been suggested that the rapidity of the alternations is too great to excite the nerves, or again, that the current thus generated does not penetrate the conductor, but traverses only its surface. An explanation would seem to me to be that the current strength of what seems to be a killing current is comparatively small, since it is reduced enormously by each "step up" transformation. But other explanations are advanced.

In the immunity from pain and muscular contraction observed. by D'Arsonval with a low frequency and a current strength of 5 amperes, another explanation must be sought for, and this is the comparatively gradual rise and fall of potential characteristic of the sinusoidal current, and physiologically vastly different in its effects from the impulsive rush of the condenser currents of Tesla and myself. D'Arsonval's high rate of frequency is obtained from an alternator and from induction coils, and condensers.

Whatever effects are to be obtained from Tesla currents must: be obtained:

a. By the direct passage of the current through the person.

b. By this means, and by taking into account the lateral electrostatic surgings outward from this direct current.

c. By interposing the patient within the rapidly alternating. electrostatic stresses constituting the field between the terminals, and yet not in contact with them.

Electro-dynamic induction effects need not probably be taken. into account.

The extended physiological effects of the Tesla currents have yet to be investigated, since no apparatus has been available to physicians or physiologists, but judging from the powerful effects upon human beings of the currents of electrostatic machines whose output is more feeble in total energy, even if equal in potential, these currents seem to me to promise most interesting and most fruitful results.

We can in our imagination picture a future group of patients pursuing any agreeable occupation, reading, conversing, playing games, and so on, in a room whose two opposite walls are of metal connected to the two terminals of a Tesla apparatus, and thus submitted to a furious molecular bombardment in the intervening space. We can imagine the surprise of the new comers, as they see the vacuum tubes carried in their hands burst into a glow of light when they are brought within the influence of the magical and invisible stream. We know that their temperatures would be raised by the bombardment, and we cannot help believing, though awaiting the proof, that profound alterations in their nutritional processes would be produced, whose influence would be far reaching in the cure of disease, particularly of the functional type.