Tesla's wireless house lighting scheme:
http://www.frankgermano.net/nikolatesla2.htm - lost source
This was the first step towards a practical wireless system. The most striking result obtained – two vacuum tubes lighted in an alternating electrostatic field while held in the hand of the experimenter. The wireless energy transmission effect involved the creation of an electric field between two metal plates, each being connected to one terminal of the induction coil’s secondary winding. Once again, a light-producing device was used as a means of detecting the presence of the transmitted energy.
The ideal way of lighting a hall or room would, however, be to produce such a condition in it that an illuminating device could be moved and put anywhere, and that it is lighted, no matter where it is put and without being electrically connected to anything. I have been able to produce such a condition by creating in the room a powerful, rapidly alternating electrostatic field. For this purpose I suspend a sheet of metal a distance from the ceiling on insulating cords and connect it to one terminal of the induction coil, the other terminal being preferably connected to the ground [type-one]. Or else I suspend two sheets as illustrated in Fig. 29 / 125, each sheet being connected with one of the terminals of the coil [type-two], and their size being carefully determined.
An exhausted tube may then be carried in the hand anywhere between the sheets or placed anywhere, even a certain distance beyond them; it remains always luminous. (Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination by Nikola Tesla - Columbia College, N.Y., May 20, 1891, Inventions, Researches and Writings of Nikola Tesla, pp. 188-189; Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, pp. 7-8)
Transmitter type-one: a source consisting of a single metal sheet suspended a distance from the ceiling on insulating cords and connected to one terminal of an induction coil, the other terminal being connected to the ground.
Transmitter type-two: a source consisting of two metal sheets suspended a distance from the ceiling on insulating cords, each sheet being connected with one of the terminals of an induction coil.
In working to develop an explanation of the two observed effects mentioned above, Tesla recognized that electrical energy could be projected outward into space and detected by a receiving instrument in the general vicinity of the source without a requirement for any interconnecting wires. He went on to develop two theories related to these observations.
Tesla also made an assumption that Earth is a charged body floating in space.
"A point of great importance would be first to know what is the capacity of the earth? and what charge does it contain if electrified? Though we have no positive evidence of a charged body existing in space without other oppositely electrified bodies being near, there is a fair probability that the earth is such a body, for by whatever process it was separated from other bodies—and this is the accepted view of its origin—it must have retained a charge, as occurs in all processes of mechanical separation".
Tesla was familiar with demonstrations that involved the charging of Leiden jar capacitors and isolated metal spheres with electrostatic influence machines. By bringing these elements into close proximity with each other, and also by making direct contact followed by their separation the charge can be manipulated. He surely had this in mind in the creation of his mental image, not being able to know that the model of Earth’s origin was inaccurate. The presently accepted model of planetary origin is one of accretion and collision.
"If it be a charged body insulated in space its capacity should be extremely small, less than one-thousandth of a farad".
We now know that the earth is, in fact, a charged body, made so by processes—at least in part—related to an interaction of the continuous stream of charged particles called the solar wind that flows outward from the center of our solar system and Earth’s magnetosphere.
"But the upper strata of the air are conducting, and so, perhaps, is the medium in free space beyond the atmosphere, and these may contain an opposite charge. Then the capacity might be incomparably greater".
We also know one of the upper strata of Earth’s atmosphere, the ionosphere, is conducting.
"In any case it is of the greatest importance to get an idea of what quantity of electricity the earth contains".
An additional condition of which we are now aware is that the earth possesses a naturally existing negative charge with respect to the conducting region of the atmosphere beginning at an elevation of about 50 Km. The potential difference between the earth and this region is on the order of 400,000 volts. Near the earth's surface there is a ubiquitous downward directed E-field of about 100 V/m. Tesla referred to this charge as the “electric niveau” or electric level (As noted by James Corum, et al in the paper "Concerning Cavity Q," PROCEEDINGS OF THE 1988 INTERNATIONAL TESLA SYMPOSIUM, and others).
"It is difficult to say whether we shall ever acquire this necessary knowledge, but there is hope that we may, and that is, by means of electrical resonance. If ever we can ascertain at what period the earth's charge, when disturbed, oscillates with respect to an oppositely electrified system or known circuit, we shall know a fact possibly of the greatest importance to the welfare of the human race. I propose to seek for the period by means of an electrical oscillator, or a source of alternating electric currents".
Excerpt from lecture "On light and other high frequency phenomena", delivered before the Franklin Institute, Philadelphia, and the National Electric Light Association, St. Louis, 1893; Inventions, Researches and Writings of Nikola Tesla, 1894, pp. 294-373:
"Assume that a source of alternating currents be connected, as in Fig. 21 / 185, with one of its terminals to earth (conveniently to the water mains) and with the other to a body of large surface P. I think that beyond doubt it is possible to operate electrical devices in a city through the ground or pipe system by resonance from an electrical oscillator located at a central point. But the practical solution of this problem would be of incomparably smaller benefit to man than the realization of the scheme of transmitting intelligence, or perhaps power, to any distance through the earth or environing medium. If this is at all possible, distance does not mean anything. Proper apparatus must first be produced by means of which the problem can be attacked and I have devoted much thought to this subject. I am firmly convinced that it can be done and hope that we shall live to see it done."
Tesla hoped for high-power transmission, which attracted him because, if feasible, this would have eliminated the need for cables to transmit electrical power. Although he suggested some techniques for this, and apparently believed that some kind of resonance could make this possible, his ideas were associated with doubts and controversy, and it seems likely that there was no realistic method for their success. He had no technique for generation of high power microwaves, which could have been transmitted in a focussed beam, and there does not seem to be any basis for supposing that the frequencies which he was able to generate could ever have been used in any point-to-point wireless power distribution system.
However, there is some recent speculative work on very low frequency oscillations which does hint at possibilities of remarkable phenomena involving resonance of the Earth’s structure.
The above described arrangements refer only to the use of commercial coils as ordinarily constructed. If it is desired to construct a coil for the express purpose of performing with it such experiments as I have described, or, generally, rendering it capable of withstanding the greatest possible difference of potential, then a construction as indicated in Fig. 17 / 113 will be found of advantage. The coil in this case is formed of two independent parts which are wound oppositely, the connection between both being made near the primary. The potential in the middle being zero, there is not much tendency to jump to the primary and not much insulation is required. In some cases the middle point may, however, be connected to the primary or to the ground. In such a coil the places of greatest difference of potential are far apart and the coil is capable of withstanding an enormous strain. The two parts may be movable so as to allow a slight adjustment of the capacity effect. (Inventions, Researches and Writings of Nikola Tesla, pp. 172-173)
The optimized type-two transmitter consists of two elevated metal plates, each plate being connected to one of the terminals of a Tesla high-tension induction coil.
Modification of the optimized type-two transmitter. This circuit is the result of interpolation of the preceding and following diagrams, which are of historical record
The modified type-two transmitter shown above consists of two elevated metal plates, each plate being connected to one of the induction coil’s high-voltage terminals. While the coil’s left-hand primary winding remains the same, i.e., it is still closely coupled to the left-hand secondary, the right-hand primary has been removed. This means the right-hand coil is no longer energized by induction. Using Tesla’s terminology, it is now an extra coil. [Some adjustment might be required to bring the extra coil back into resonance with left-hand secondary.] The extra coil is energized or receives energy by one-wire transmission through the interconnecting section of wire.
A further modification of a type-two transmitter, this circuit represents the preferred prototype transmitter design developed in 1899 at the Colorado Springs experimental station. The transmitter circuit now consists of separate two elements, an alternator-driven oscillator and an adjacent free oscillatory system.
In the further modified type-two transmitter shown above the two halves of the transformer have been physically separated. The transmitter now consists of two discrete units. The oscillator is on the left with its elevated plate still connected to the upper secondary terminal. The free system on the right consists of the original elevated plate connected to the upper terminal of the extra coil. Instead of a wire connecting the lower secondary and lower extra coil terminals, the two coils are now connected to individual earth grounds. These ground connections are constructed so as to introduce the least possible resistance to the earth. In operation a powerful current flows through the subsurface between the two ground terminals. An interaction also takes place between the two elevated terminals. Tesla believed the electrical disturbance would extend to a great distance from the transmitter, possibly across the globe.
http://www.frankgermano.net/nikolatesla2.htm - lost source
The question arises as to the cause of the failure reported the 1903 letter to J.B. Morgan. Is the two-coil/two ground concept fundamentally flawed, or was the problem in its’ single-tower implementation? It’s possible the earlier type-two transmitter tests were performed using plant’s chimney-mounted lightning protector as an elevated capacitance in conjunction with the laboratory-side pancake coil, aka the New York oscillator. In this case the tower-side transmitting element would have been a passive extra-coil helical resonator connected to the tower’s cupola and grounding structure. This would have represented a true type-two transmitter, however the amount of power that could have been processed by the alternator-driven oscillator would have been limited by its’ relatively small size.
In the 1925 paper “Wireless power system using the surface of the earth as a conductor,” John B Flowers, H.L. Curtis, J.H. Dillinger, Radio Laboratory, Bureau of Standards, Washington, D.C. [Harnessing the Wheelwork of Nature, pp. 22-23] a statement is made regarding the feasibility of using 60 cycles-per-second as the systems fundamental frequency. An electric generator is connected with wires to ground points 750 miles apart. Although not a true Tesla wireless apparatus, the design does suggest a type-two transmitter.
In 1932 journalist J.J. O’Neill conducted an interview with Tesla in which he makes a distinction between the transmission of electrical energy by atmospheric conduction and earth resonance principles.
I also asked him if he is still at work on the project which he inaugurated in the '90's of transmitting power wirelessly anywhere on earth. He is at work on it, he said, and it could be put into operation. He at that time announced two principles which could be used in this project. In one the ionizing of the upper air would make it as good a conductor of electricity as a metal [using a type-one transmitter]. In the other the power would be transmitted by creating "standing waves" in the earth by charging the earth with a giant electrical oscillator [of the type-two design] that would make the earth vibrate electrically in the same way a bell vibrates mechanically when it is struck with a hammer. "I do not use the plan involving the conductivity of the upper strata of the air," he said, "but I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe." (“Tesla Cosmic Ray Motor May Transmit Power 'Round’ Earth,” Brooklyn Eagle , July 10, 1932, John J. A. O'Neill)
In 1934 the following drawing of a large type-two transmitter appeared in an article on wireless power transmission.
The caption reads, “Nikola Tesla, electrical wizard, foresees the day when airplanes will be operated by radio-transmitted power supplied by ground stations, as shown” (Transmitter type-two, C/S #6; "Radio Power Will Revolutionize the World," Modern Mechanix and Inventions, July 1934, Tesla Said, pp. 261-266)
This suggests that the problem was, in fact, the single-tower implementation, and at some point prior to 1932 Tesla validated the type-two launching structure configuration using two properly spaced top-loaded helical resonators.
One additional observation needs to be made before leaving the subject of the initial Wardenclyffe circuit configuration. Some descriptions of the Wardenclyffe tower include a vertical conductor extending from the bottom of the 120 shaft below the tower up to the under side of the cupola. One account by Anderson on 1969 states:
Excitation currents pulsed through a 16-section telescoping shaft that rose under air pressure 300 feet from the bottom of the well to contact the spherical terminal.
and another by Popovic on 1976:
Radio station on Long Island consisted of a large building and a special antenna tower suspended on a wooden pyramid of several meters in diameter with a changeable height position by means of a metal tube which was telescopically vertically moveable, was emerging from a cylindrical 30 m deep hole in the ground beneath the pyramid.
A direct electrical connection between the elevated isotropic capacitance and the subterranean ground connection would be consistent with the type-two transmitter design. Note that the as-built tower legs were made of wood—not metal—necessitating the conducting shaft. Also, placement of the ground connection at the bottom of the 120-foot excavation might have been a way to partially compensate for height lost in the initial design changes. Tesla’s original plans called for an overall tower height of 600 feet.
To properly supply the world’s need for power, it would have taken a series of transmitting towers. The towers’ ground connection is absolutely critical, so there’s a good chance that the majority of the towers would be close to large quantities of salt water. Coastlines and islands such as Hawaii, the British Isles and similar places would have been ideal locations.
Other suitable locations rich in conducting minerals would undoubtedly have been found. Sites of old abandoned copper; silver, gold and mercury mines could have been converted into tower sites. In some cases, steel rails for the ore carts to roll on would have been left in place. They could have been used for additional grounding. Other possible locations include areas abundant with salt such as: Salt Lake City, Bonneville, The Dead Sea, New Orleans and Detroit, Michigan.
Tesla believed that the upper portions of the atmosphere were very conductive for high voltage electricity. It is speculated that Tesla planned to use a high voltage ionizing beam, aided by ultra violet light, to serve as an electrical conduit to the upper regions of the stratosphere. Airplanes and other airships could then draw the necessary current to power their motors. This would have been ideal for zeppelins and blimps. They would have less weight because they would carry little or no fuel. In addition, they would use dependable and light weight electrical motors instead of the heavier and more complicated fuel powered engines.
Good sized ships, yachts and ocean going vessels could have the necessary equipment/apparatus to send up its own ionizing (probably aided by a laser beam) ray to plug into the power grid in the sky.
llustrations from an article in the March, 1920 issue of Electrical Experimenter entitled "Wireless Transmission of Power Now Possible". The illustrations show his prototype devices for "directed ionized beam transmissions," a "deathray—searchlight" device. But according to Tesla, the results of tests did not justify the hope of important practical applications in large distance.
"After preliminary laboratory experiments, I made tests on a large scale with the transmitter referred to and a beam of ultra-violet rays of great energy in an attempt to conduct the current to the high rarefied strata of the air and thus create an auroral display such as might be utilized for illumination, especially of oceans at night. I found that there was some virtue in the principal but the results did not justify the hope of important practical applications although, some years later, several inventors claimed to have produced a "death ray" in this manner. While the published reports to this effect were entirely unfounded, I believe that with the new transmitter to be built, many wonders will be achieved".
Tesla's Flashes Startling - New York Sun - July 17th, 1903:
“It is true that some of them have had to do with wireless telegraphy and that in addition to the tower and poles there is a hole dug in the ground. This is 150 feet deep and is used in these experiments. The people about there, had they been awake instead of asleep, at other times would have seen even stranger things. Some day, but not at this time, I shall make an announcement of something that I never once dreamed of.”
Tesla's New Discovery - New York Sun - January 30th, 1901:
“It is probable that we shall perfect instruments for indicating the altitude of a place by means of a circuit, properly constructed and arranged, and I have thought of a number of other uses to which this principle may be put.”