Nikola Tesla in Colorado Springs

 

 

Courtesy of Rex Hebert 
 
 
Tesla dedicated most part of his research to develop the right design of a wireless power transmission system to be able to energize the whole planet without wires and to send signals or messages instantly and non-transferable.
 
Excerpt from "On electricity" - Electrical Review - Jan. 27, 1897:
 
"In fact, progress in this field has given me fresh hope that I shall see the fulfillment of one of my fondest dreams; namely, the transmission of power from station to station without the employment of any connecting wires."
 
Tesla's went to Colorado Springs in mid-May 1899 with the intent to research:
 
1.   Transmitters of great power.
2.   Individualization and isolating the energy transmission means.
3.   Conditions of propagation of currents through the earth and the atmosphere.
 
In early 1902 Tesla sent a letter to J.P.Morgan to explain his research in which he evisaged the following distinct steps to be made:
 
1.    The transmission of minute amounts of energy and the production of feeble effects, barely perceptible by sensitive devices;
2.   The transmission of notable amounts of energy dispensing with the necessity of sensitive devices and enabling the positive operation of any kind of apparatus requiring a small amount of power;
3.   The transmission of power in amounts of industrial significance. With the completion of my present undertaking the first step will be made.
 
Tesla spent more than half his time researching transmitters. Tesla spent less than a quarter of his time researching delicate receivers and about a tenth of his time measuring the capacity of the vertical antenna. Also, Tesla spent a tenth of his time researching miscellaneous subjects.
 
J. R. Wait's comment on Tesla activity:
 
"From an historical standpoint, it is significant that the genius Nikola Tesla envisaged a world wide communication system using a huge spark gap transmitter located in Colorado Springs in 1899. A few years later he built a large facility in Long Island that he hoped would transmit signals to the Cornish coast of England. In addition, he proposed to use a modified version of the system to distribute power to all points of the globe".
 
The authors note that no alterations have been made to the original which still contains certain minor errors; calculation errors which influence conclusions are noted. The authors also note the end of the book contains commentaries on the Diary with explanatory notes.
 
 

 
Courtesy of Rex Hebert 
 
 
Already in a meeting of the National Electric Light Association on 1893, Tesla told:
 
“practical to disturb, by means of powerful machines, the electrostatic conditions of the earth, and thus transmit intelligible signals, and, perhaps, power”
 
He said,
 
“It could not require a great amount of energy to produce a disturbance perceptible at a great distance, or even all over the surface of the earth.”
 
By the end of the 1890s Tesla had come to the conclusion that it might be possible to transmit electrical power without wires at high altitudes where the air is thinner, and consecuently it is more conductive.
 
In a patent US645,576 - System of Transmission of Electrical Energy - March 20, 1900 Tesla claimed:
 
"it has become possible to transmit through even moderately rarefied strata of atmosphere electrical energy to practically any amount and to any distance."
 
A friend and patent lawyer, Leonard E. Curtis, on being advised of Tesla's scheme, offered to find land and provide power for his research from the El Paso Power Company of Colorado Springs. The next supporter to come forward was Colonel John Jacob Astor.
 
After receiving large donations from several wealthy friends, Tesla arrived by Train to Colorado Springs on May 17 or 18, 1899 and was met by Leonard Curtis. He brought the inventor riding by horse to the Alta Vista Hotel, located on Cascade Avenue between Kiowa Street and Bijou Street in Colorado Springs, El Paso County, where he resided during his stay in Colorado.
 
A group of reporters were already waiting for Tesla in the hotel. One of those reporters asked to him about the reasons why he decided to chose Colorado to develop his research. Tesla replied:
 
"I might as well tell you the truth, I have come here to carry on a series of exhaustive experiments in regard to wireless telegraphy. I come here for work."
 
The reporter asked again:
 
"Are you going to flash (his) message from Pike's Peak to Long's Peak or another mountain of Colorado?"
 
The question appeared unconfortable to Tesla who tersely replied:
 
"No, I am here to work. It is not pleasure. I am very busy and life is short and there is a great deal to be done."
 
When the interview was finished he retired to his room number 207. Tesla needed some conditions to feel confortable: He allways preserved his obsession with the number 3 and all numbers divisible by this number and there should never be an exception in many of his every day tasks. He preferred to choose a room on the ground floor or little height because the lifter would be unnecessary for any emergency. Another condition which was indispensable for Tesla was that the maid service had to be exelent because of his germ-phobia. This obsession began in his youth, and it continued growing more and more demanding as the years passed by. In this occasion Tesla requested extra linens and 18 clean towels a day, saying he liked to do his own dusting.
 
The journalists reported that Tesla seemed to be distracted by some important thoughts and not paying so much attention to give answers to their questions. He was probablly anxious for his assistant and equipment to arrive in Colorado Springs to be able to begin his work. He arrived a few days ahead of his assistant Fritz Lowenstein and he had time for some important people of the local society to entertain Tesla at places such as The El Paso Club, and all men's club downtown. For a creative exploration into the mind of Tesla while he awaited Lowenstein's arrival.
 
By 1899, his laboratory in New York was too small to carry out the further experiments needed to answer the questions about the earth’s electrical properties and resonant frequency. His idea was to develop new experiments on powerfull oscilators and his laboratory wouldn't have enough space for the big spiral coil. When that coil was operated at 3 million volts, it could send arcs out striking the ceiling and walls.
 
Many of his general plans had already been pirated and he could not risk any more losses due to spy activity. He longed for open space and privacy. After secretly searching the country for the best location for his new lab, Tesla decided on Colorado Springs. This decision was based on many factors, the foremost being free land and electricity from the Colorado Springs Electric Company. Tesla also discovered that the area was ideal for conducting electrical experiments as well as observing the immense electrical storms of the region.
 
 
 
Tesla later wrote:
 
"The conditions in the pure air of the Colorado Mountains proved extremely favorable for my experiments, and the results were most gratifying to me. I found that I could not only accomplish more work, physically and mentally, than I could in New York, but that electrical effects and changes were more readily and distinctly perceived."
 
The inventor though that this location would be favorable for his experiments primarily because of the frequent thunderstorms, the high altitude (where the air, being at a lower pressure, had a lower dielectric breakdown strength, making it easier to ionize), and the dryness of the air (minimizing leakage of electric charge through insulators).
 
He was experimenting with his incredible electrical displays to measure and to analize the results and he soon found some electrical vibrations of earth. After analizing such results he came to the conclusion that it was caused by lightning when it struck the ground. He believed that when this happends the discharge of the lightning could cause powerfull waves that would move from one side of the earth to the other extreme. For this reason he considered that the earth could act as a conductor to transmit unlimited amounts of power to any place on the earth surface with a minimum loss. To test his theory he had to develop his designs to be the first man to reproduce electric effects on the scale of lightning.
 
The inventor prepared his design to build an oscilator many times more powerfull than anyone he had worked in the past. He had the suspicion that by using such design it would be appropiate to determine if it could be possible to produce a resonance effect enough powerfull to produce some influence in the earth resonance, but he also had the objective to develop high powered tests of wireless comunication systems.
 
Tesla and his assistants started construction of the new lab shortly after arriving in Colorado Springs. Aided by local contractor Joseph Dozier, they provided a bit of land on the prairie that was located on Knob Hill, at east of the Colorado School for the Deaf and the Blind (which still operates to this day) and 1 mile (1.6 km) east of downtown.
 
The primary purpose of his plan were to develop experiments with high frequency electricity and other phenomena and, secondarily, research into wireless transmission of electrical power.
 
 
The Colorado Springs laboratory & the magnifying transmitter

 

 
3D modeling by Vladimir Jaksic, Marko Novakovic, Milos Novakovic, Nikola Stojanovic.
 
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Tesla's acceptance speech on receiving the Edison Medal, May 18, 1917
 
"I have learned how to put up a plant that will develop a tension of 100,000,000 volts and handle it with perfect safety. This plant (indicating) was in Colorado. It was a square building, in which there was a coil 52 feet in diameter, about nine feet high. When it was adjusted to resonance, the streamers passed from top to bottom and it was a most beautiful sight. You see, that was about fifteen hundred, perhaps two thousand square feet of streamer surface. To save money I had calculated the dimensions as closely as possible, and the streamers came within six or seven inches from the sides of the building. For handling the heavy currents, I had a special switch".
 
The laboratory that began to rise from the prairie floor was both wired and weird, a contraption with a roof that rolled back to prevent it from catching fire, and a wooden tower that soared up to eighty feet.
 
The design of the laboratory consisted of a building 50 feet by 60 feet (15 by 18 m) with 18 foot (24 m) ceilings. A 142 foot (43 m) conducting aerial with a 30 inch (76 cm) copper-foil covered wooden ball was erected on the roof.
 

 
 Tesla peeks out the door of the Colorado Springs Laboratory. Early summer, 1899.
 
Builders erected a high fence around the site, and signs appeared on every post - KEEP OUT. GREAT DANGER - in hopes of keeping the curious at a distance. Fritz Löwenstein could not resist posting at the door another sign, quoting Dante's Inferno: "Abandon hope, all ye who enter here."
 
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Very little is known about the exact plan of the apparatus built but also the experiments developed by Nikola Tesla in Colorado Springs laboratory except from articles written by local newspapers and, later, in articles written by himself and his diary. Tesla wrote a diary of his every day experiments in the Colorado Springs laboratory where he spent nearly nine months developing his research and $100,000 building an electrical research. The notes that do exist were never published and are now stored in the Nikola Tesla Museum in Beograd, Yugoslavia DPM - some notes published in 1978 today called Colorado Spring Notes 1899-1900. It consists of 500 pages of handwritten notes and nearly 200 drawings, ordered by dates between June 1, 1899 and January 7, 1900, as the work occurred, containing explanations of his experiments. Tesla's diary contains explanations of his experiments concerning the ionosphere and the ground's telluric currents via transverse waves and longitudinal waves.
 
The inventor kept in contact by mail with his assistant George Sheriff in the New York laboratory to discuss about some of the equipment that were under development while the new laboratory was under construction.
 
According to all the specifications, some machinery, components and electrical devices were sent from New York to Colorado Springs: balloons eight and ten feet in diameter and covered with varnish. 300 bottles with the necks ground off (probably for leyden jars), drums, oscillators and spools, 1100 feet of solid wire, and later 40,000 feet of cable. A number of storage batteries were also sent, along with nickel and aluminum chips and five grades of silver and gold filings for coherers.
 
Inside the strange wooden structure, technicians began to assemble the enormous Tesla coil. The device used a 50,000 volt Westinghouse transformer to charge a capacitor that consisted of a galvanized tub full of salt water as an electrolyte, into which he placed large glass bottles, themselves containing salt water. The salt water in the tub was one plate of this capacitor, the salt water inside the bottles the other plate, and the bottle glass the dielectric. Various capacities were tried, incremental changes being made by connecting more or fewer bottles. A variable tuning coil of 20 turns was connected to the primary, which consisted of two turns of heavy insulated cable that ran around the base of the huge fence like wooden secondary framework. The frame on which the heavy primary and secondary coil were wound had a diameter of 52 feet (16 m), and ??-turns (17 or 24 turns according with 2 different sources). Various extra coils were tried, and the final version was 12 feet high by 8 feet in diameter, and having 100 turns of wire. It was connected to the secondary in order to amplify the electrical effectsthrough a process called "resonant rise." This enormous air-core transformer could deliver a current of 1,100 amperes. The function of this coil was not understood until the 1970s.
 
An extra coil gives the resonant boost of a tesla coil secondary but has the advantage of being more independent. A secondary, being closely slaved to the primary, is inhibited somewhat by it, its oscillations slightly damped. The extra coil is able to swing more freely. Tesla told:
 
"Extra coils enable the obtainment of practically any emf, the limits being so far remote that I would not hesitate to produce sparks of thousands of feet in this manner.”
 
The engineering challenge of the magnifying transmitter, then, becomes one of containing and properly radiating its “immense electrical activities, measured in the tens and even hundreds of thousands of horsepower,”
 
The antenna was a 30-inch conductive ball adjustable for height on the mast, and he huge transmitter could vibrate from 45 to 150 kilocycles.
 
 
 
View of interior showing half of a circle of oscillator frame with several coils grouped inside; Westinghouse transformer, lightning arresters in background, also part of central extra coil latest pattern and a 30" ball on stand. The photograph was taken late in the afternoon.
 
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The inventor designed and constructed the largest Coil ever built in his laboratory to be able to carry out his experiments. The design wasn't the same one as a classic Tesla Coil but it was a three-coil magnifying system requiring different forms of analysis than lumped-constant coupled resonant coils presently described to most. It resonated at a natural quarter wavelength frequency and could work in a continuous-wave mode and in a partially damped-wave resonant mode. According to accounts, Tesla used it to transmit tens of thousands of watts of power wirelessly; it could generate millions of volts of electricity and produce lightning bolts more than 100 feet (30 m) long. At his lab Tesla proved that the earth is actually transmiting electricity as a conductor, and he produced artificial lightning with discharges consisting of millions of volts, and up to 135 feet long.
 
 
 
Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers
 
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Tesla began coiling inside the building at Colorado Springs on June 15, 1899 and he had two metal to earth connections available, the water pipe and the lightning arrestor ground. Tesla notes:
 
"Sparks went over the lightning arrestors instead of going to ground. This made it necessary to change the connection to the ground, separating that of the secondary of the oscillator from the ground of the arrestors. By connecting the secondary to a water pipe, and leaving the ground of the arrestor as before, the sparks ceased. This indicates a bad ground on the arrestors. The latter worked exceedingly well. The ground connection was made by driving in a gas pipe about 12 feet deep and gammoning coke around it. This is the usual way as here practised."
 
First note that arcing was occuring from the earth connection over the arrestors. This shows that the lightning arrestor ground, an iron gas pipe driven twelve feet into the earth, was insufficient for even a low power test. Tesla clearly recognizes the differences between the two grounds he has available. The capitalized sentence above was in italics in the original. His setup is brand new. His tune is rough.
 
The following day, June 16, 1899, he had workmen going full tilt on a dedicated RF ground for his experiments.
 
"A new ground connection was made by digging a hole 12 feet deep and placing a plate of copper 20" x 20" on the bottom and spreading coke over it again, as customary. Water was kept constantly flowing upon the ground to moisten it and improve the connection but in spite of this the connection was still bad and to a remarkable degree. It is plain that the rocky formation and dryness is responsible and I think that the many cases of damage done by lightning here are partially to be attributed to poor earth connections. By keeping the water constantly running the resistance was finally reduced to 14 ohms between the earth plate and the water main."
 
Tesla clearly notes the indivuality of the water pipe and the earth plate, just as earlier he noted the difference between the arrestor ground and the water pipe. We could call the earth plate the "dedicated RF system ground" or simply "system ground".

In text following the quote above, Tesla next refers to using a "sensitive device" to determine the presence of a ground current around the lab.

Apparently the water was turned off that night, for on the following day, June 17, 1899:
 
"Measurements of resistance between ground wire and water mainshowed the surprising fact that it was 2960 ohms, and even afterhalf an hour watering it still was 2400 ohms, but then by continued watering it began to fall rapidly. Evidently the soil lets the water run through easily and being extremely dry as a rule it is very difficult to make a good connection. This may prove troublesome. The water will have to be kept flowing con-tinuously. The high resistance explains the difficulty, from a few days before, of getting the proper vibration of the secondary. The first good ground was evidently at the point where the water main feeding the laboratory connected to the big main underground and this was several hundreds of feet away. This introduced additional length in the secondary wire which became thus too long for the quarter of the wave as calculated. The nearest connection to earth was as measured about 260 feet away and even this one was doubtful."
 
Tesla has told something clear. First his measure of resistance when the water is off overnight skyrocketed. Though the water expense was unbudgeted, it ran 24-7. (The bill was finally paid when the wood used in construction was sold after the building was dismanteled.). This shows that Tesla was determined that no expense was to be spared in obtaining the lowest resistance ground connection possible.

Tesla then notes that the first true electrical ground point occurs on the water main at the junction to the laboratory supply pipe. He notes at the end of the quote that even this ground point is doubtful, possibly because his equipment is powerful enough to push the center of the "true electrical ground point" further up the main.

Tesla also notes that the ground path leading to the true electrical ground point must be considered as a parasitic conductor length in all secondary calculations. This distance between the base of the secondary coil and the "true ground" affected his ability to determine the resonate frequency of the grounded coil and kept him from establishing a sharp tune in the system. Add the fact that the location of the true electrical ground point on the pipe may not be stable, and would possibly move farther away with increasing power levels, meant that the water pipe would be completely unsatisfactory for use as the system RF ground.

To jump ahead to page 125, the section notes indicate that stationary standing waves were observed on the water pipe, and the exact electrical distance from the ground plate to the electrical node on the pipe was determined to be 550 feet. This would be an unpleasant amount of uncoupled conductor to add to any secondary coil.

In conclusion, Tesla recognized the need for a dedicated RF ground in his coil systems. His specifications were such that the true electrical ground point for the system ground had to lay as close as possible to the base of the secondary coil. He recognized the need for a highly conductive pathway adapted for low frequency high-voltage RF.
 
 

 
Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers
 
 
View of interior, chiefly showing condensers, brake motor and regulating coil in primary of oscilator. Westinhouse high tension transformer and supply of transformers background, also arresters.
 
Oscilating apparatus on a large scale coil at left 51 feet diameter, forms part of the magnifying transmitter.
 
 
 
Nikola Tesla's experimental station at Colorado Springs. Interior close up, of oscillator components including condensers, regulating coil, and Westinghouse high tension transformer. December 1899.
 

 photographic view of the essential parts of electrical oscilator used in Tesla's experiments.
 
 
⦁    Orange - copper primary magnifier transmitter winding
50 feet in diameter
157 feet in circumference
50 turns
7854 feet long
3/16" x 3/4" copper bar (.545 Lbs. per foot)
4280 pounds of copper for "primary" coil
NSRW Alloy 110 Copper Bar Stock (copper bar weights)
 
⦁    Green - fourteen (14) metal condensers or capacitors boxes
(oil filled) 15-20 gallons each
 
⦁    Red - one (1) High Voltage Transformer
(oil filled) 20-30 gallons
 
⦁    Yellow - Oscillator with hand crank
 
⦁    Turquoise - two (2) metal Oscillator switch boxes
(oil filled) 15-20 gallons each
 
This is just one photograph not including the 75 KW generator set that was in pieces for easy moving plus the fuel, then there are other photograph with the secondary coil in the center of the primary coil plus the grounding grid under the floor then there is the switch gear needed.
 
 
 
One of Tesla's assistants posed at the variable-inductance crank in the primary circuit of the large Colorado Springs experimental station oscillator (1899). The primary winding was a heavy, two turn, multi-strand cable 50 feet in diameter. Note the long insulated handle on the crank. - Photo by Carl Duffner
 
 
 
Tesla's experimental station at Colorado Springs. Shown is an ante room off the main experimental area. An X-ray photographic cabinet can be seen on the table, and underneath the table an electric heater. It should be pointed out that this was the only source of heat in the cold winter days from October to January 1900 when Tesla returned to New York City. 1899.
 
 
Experiments in Colorado Springs Laboratory

 

 Front view of the Colorado Springs experimental station, with Union Printers Home in background. A special coil wound for investigation of the influence of elevation upon the capacity of an elevated conductor is visible in front of the laboratory. 1899
 
Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers

 

 This publicity photo taken at Colorado Springs was a double exposure. Tesla poses with his "magnifying transmitter" capable of producing millions of volts of electricity. The discharge here is twenty-two feet in length.
 
The first experiments in Colorado Springs Experimental Station were performed on June, 15th. Tesla records his initial spark length at five inches long, but very thick and noisy.
 
Tesla got to the conclusion from his experiments in Colorado that power transmission only through the earth would probably not be practical, but he was still able to produce some surprising demonstrations of this within a radius of 25 miles or so.
 
He also described a number of very unusual phenomena related with the Magnifying Transmitter. When it was dark, a person walking near the building would notice sparks forming between his feet and the ground or it was even possible to appreciate some sparks between the grains of sand. This phenomena was caused when the ground of the laboratory was highly charged because the secondary coil was energized while producing 20 to 30 foot discharges inside the laboratory as described earlier. The ground near the lab would be charged so strongly that arcs of an inch in length could be drawn from a water main 100 feet away.
 
When Tesla operated his apparatus at 4 milion volts, he could stand 60 feet from the laboratory holding a light bulb and the filament would quickly shatter because of the violent fluctuations. Some strange effect that was observed was that the butterflies would sometimes caught up and whirl around the laboratory building like if it were a hurricane. It is known that albeit strange, small Tesla Coils and Van DeGraff machines could cause a similar display with small bits of foil.

 

Receiving devices
 
The inventor preformed some experiments with a sensitive receiving device before the oscillator was completed, with which he was investigating the electrical activity of the earth. The device consisted of a primary coil with a large number of turns, the bottom of which was grounded and the top connected to an elevated terminal of adjustable capacity. In a secondary circuit, made up of several turns of wire near the base of the primary, a sensitive detector or coherer was located. Coherers were a vacuum tube filled with powdered oxidized metal which conducted electricty when exposed to radio frequency energy.
 
Many of his coherers utilized a small hammer-like device to tap the tube after each signal, breaking up the filings and increasing the resistance in preparation for the next signal. A number of ingenious mechanisms such as shakers were developed for decoherence.
 
Reproductions of Tesla's receivers and coherer circuits show an unpredicted level of complexity (e.g., distributed high-Q helical resonators, radio frequency feedback, crude heterodyne effects, and regeneration techniques).
 
Years before vacuum tubes and a half century before transistors, Tesla's vessel was equipped with a clever but much more primitive means to detect signals from the radio-control transmitter.
 
Incoming radio signals were just strong enough to jostle the metal granules (d) into a configuration where they could conduct electricity and trigger the motor or rudder. To reset the detector, a motor would flip the detector end-over-end like an hourglass.
 

US613,809 - Method of and apparatus for controlling mechanism of moving vehicle - November 8, 1898

Tesla also constructed many smaller resonance transformers and discovered the concept of tuned electrical circuits. He also developed a number of coherers for separating and perceiving electromagnetic waves and designed rotating coherers which he used to detect the unique types of electromagnetic phenomenon he observed. They had a mechanism of geared wheels driven by a coiled spring-drive (or clockwork drive) mechanism which was used to continuously rotate the small glass cylinders thus decohering the chips after each received impulse from lightning strikes. These experiments were the final stage of years of work on synchronized tuned electrical circuits. It is now believed by Dr. James Corum that coherers are uniquely suited to detect the particular type of natural radio phenomenon that Tesla observed in 1899.
 

Special clock constructed for purpose of measurements, espacially usefull in receiving. Described in lecture before The New York Academy of Sciences, 1987.

 Illustrating some of the attachments and mode of using the same. Houston Street Laboratory, 1898-1900.

These transceivers were constructed to demonstrate how signals could be "tuned in". Tesla logged in his diary on July 3, 1899 that a separate resonance transformer tuned to the same high frequency as a larger high-voltage resonance transformer would transceive energy from the larger coil, acting as a transmitter of wireless energy, which was used to confirm Tesla's patent for radio during later disputes in the courts. These air core high-frequency resonating coils were the predecessors of systems from radio to radar and medical magnetic resonance imaging devices.
 
 

 
Colorado Springs Notes - July 23, 1899
 
In investigating the propagation through the media, and more particularly through the ground, of the electrical disturbances produced by the experimental oscillator, as well as those caused by lightning discharge, to which work a few hours were so far devoted every day, a form of sensitive device used in some experiments in New York was adopted, as the best suitable for these purposes.
 
This device, and the manner of preparing it, it is now necessary to describe. In one form it comprised a glass tube 3/8" inside diameter, having two brass plugs fitted in its ends. The plugs had their inner surfaces highly polished and the distance between them was from 1/8"—1/2". The tube is illustrated in Diagram 1. in which a is the glass tube and b b\ the plugs of metal with narrow projections C C\ for support and contact, respectively.
 
The space between the plugs was filled about 1/3 full with coarse chips of nickel. These chips were made by a milling tool or punch so as to be as much as possible equal in size and shape, this being of considerable importance for the good performance of the instrument. The plug b had a small reamed (tapering) hole h in the center extending to some distance into the plug so as to enable its being placed on a small arbor fitting into the hole and rotated by clockwork at a uniform rate of speed.
 
In some cases when the working of the device was excellent the speed was 16 revolutions per minute. But often the instrument was rotated very much faster in which case it was merely necessary to increase the e.m.f. of the battery which was used to strain the device to the point of breaking down. A beautiful feature of this kind of device is that by regulating the speed its sensitiveness may be regulated at will and in this respect it is preferable to similar devices which are stationary, the contact after being established being broken by tapping.
 
The device acts exactly like a cell of selenium, its resistance diminishing when the disturbances reach it, being automatically increased in consequence of rotation and separation of the chips when the disturbances cease to affect the latter. The rotation of the device replaces here the property of recovery which the selenium possesses, otherwise the similarity is complete. To insure a quite satisfactory working and permanent state I prepare this form of device in the following manner:
 
The glass tube, plugs and the chips to be used are first thoroughly cleaned with pure absolute alcohol and dried. Next, one of the plugs, as b, is slipped into one end of the glass tube and the required amount of chips is put in the other, plug bt being finally inserted closing the tube nearly hermetically, but not quite so. Now the device is placed upon a cylinder of metal with a hole in the center, to allow the small part of one of the plugs b or b1 to slip in, with some space between, and permit the plug to rest upon and in good contact with the upper surface of the metal cylinder which is then slowly heated, as by being placed upon an electrical stove or a plate supported above an alcohol lamp.
 
When the lower plug is brought to the required temperature, sealing wax is run around the rim projecting for this purpose, beyond the glass tube. The metal cylinder is now allowed to cool down slowly until the sealing wax is in some degree solidified when the instrument is turned over and placed with the other plug on the cylinder and the operation of sealing the joint between glass and plug repeated.
 
During this preparation the chips are of course at an elevated temperature and all moisture is expelled so that, when the instrument is ready, a thoroughly dry atmosphere exists within the same, this being essential for good performance. The atmosphere is, however, at a pressure slightly below that of the surrounding air. When the device is carefully prepared it works remarkably well, and in comparative tests showed itself superior to this kind of device of the form ordinarily advocated.
 
During a few days I carried on tests of this kind which brought out the good qualities of this kind of instrument. In one instance two of them were compared with a third device of the ordinary form in which the sensitive grains were immersed in an atmosphere considerably rarefied and contact was broken with a tapper.
 
In all three instruments the grains of nickel were of the same size and shape. One of the terminals of each of the devices was connected to a ground wire, while the other terminals were each joined to a piece of wire extending to a small height, these pieces of wire being the same in all particulars.
 
All the three devices were strained as far as was practicable by batteries so as to be at the point of breaking down and sensitive to a high degree. Although the pieces of wire extending into the air were only of a length of a few feet, all the instruments recorded the discharges of lightning up to about 30 miles as the storm moved away. At this point it was found necessary to set the instrument with the "tapper" so that it was still more sensitive when it responded but in an irregular manner, while the other two devices continued to record regularly up to a distance of about fifty miles when the disturbances ceased, probably owing to the cessation of the storm.
 
I inferred from these experiments, carried on for some time with the view of selecting and adopting the best form of such a device, that when the particles of metal are rotated they are, as it were, suspended in the air and in this condition more susceptible to the influence of the disturbances than when they are kept stationary. It seems, however, that when rotated, the particles are not so liable to stick together and cause irregularity of action such as observable in the ordinary form of such a device.
 
As to the amount of chips, if more are put in the instrument must be rotated at a higher speed or else the battery straining the dielectric must be weaker. Through this kind of instrument much stronger currents can be passed without damaging it and making it further unfit for work.
 

 
Another form of such instrument particularly suitable for experimentation is illustrated in Diagram 2. It consisted of a brass plug b with a fiber tube into which was fitted another brass or metal plug bi which was held in place by a fiber washer/j and metal nut n. In other devices of similar construction the space between the plugs was adjustable. This form of instrument was particularly suitable for testing the properties of sensitive grains g.
 
Before testing the grains and the instrument as well were thoroughly dried. To get an idea of the resistance of such devices when in either state, excited or not, the resistance of many was measured under varying conditions. A fair idea is conveyed by saying that, unexcited, they measured more than 1,000,000 ohms while the resistance would sink down to 300 or even 50 ohms or still less when excited. When highly sensitive they would respond to sound waves at a considerable distance.
 
Experiments with oscillator 35 turns in secondary on tapering frame No. 10 - B. & S. wire.
 
This is the first test of the Westinghouse transformer installed a few days ago. It was tried yesterday evening but only for a short time to merely get an idea how it will behave. The e.m.f. used was 7500 volts or less. Today a pressure of 15,000 volts on the secondary was used. Best resonating action was obtained with one primary turn and a few turns in the regulating coil.
 
The spark gaps were as long as obtainable in the box, that is, about 7 turns of the screw on each side, possibly an inch or so. An approximate estimate places the primary inductances at 75.000 cm. or Lp= 75/106 H. The primary capacity was 88 jars in each of the sets in series. The capacity of one jar being approximately 0.0035 mfd.
 
The total capacity Cp is=0.154 mfd. From this calculated, and neglecting as in most cases before the reaction of the secondary, we get T= 214/107 or n=46,730 per second.
 
Observations: A spark gap being established between the free terminal of the secondary and an earthed wire, strong streamers were seen on the latter. This shows very rigorous action and demonstrates that the potential of the neighbouring parts of the ground must be considerably affected. Very strong sparks on lightning arresters as the secondary discharge is playing over the gap. This is certainly extraordinary as the ground is now excellent on trie secondary.
 
The arc, horizontally passing about 32" long is very powerful, thick and giving a vivid light, the noise is deafening. The arc passes sometimes on a downward course. Is, it attraction or due to surgings of the air in consequence of violent explosions? When large balls 30" diam. are placed in the gap the spark length is nevertheless small. This shows the secondary can not supply the great amount of energy necessary for charging the large balls to full pressure.
 
This may be due simply to the imperfect inductive connection with the primary or to the small amount of power now available from the supply transformers, as there are only two of them, and the Westinghouse transformer works only at 1 /4 of the normal pressure. This would mean roughly 1 /16 of its total performance. On some points of the balls small streamers are observed; must be due to roughness or points on the places.
 
The balls will have to be gone over and all the surface polished up. It would be impossible for streamers to break out from balls of such size unless the pressure is a few millions of volts, which cannot be the case at present. A curious feature is to see the sparks deviate and follow wooden beams or planks placed nearby. I rather think this is merely due to an effect of the currents of air which are prevented from circulating freely on the side of the plank or beam.
 
The intensity of the vibration in the primary is evidenced by sparks passing between the turns of the regulating self-induction coil in the primary. Between the beginning and end of the coil, although only a few of the turns are inserted, the sparks are sometimes 3" long. This shows a very high e.m.f. on the primary and I almost think there must be a mistake as to the pitch estimated which, judging from these sparks, would seen to be much higher.
 
This is to be investigated closer. Experimentation shows that it is very decidedly better to adopt one turn of primary instead of two and if a lower frequency is desired rather to increase the primary capacity. With one turn the explosions are more violent and the regulation is much more convenient. In these experiments the jars do not seem to be much strained, which indicates well.
 
At times sparks will break through inside of the secondary between the turns and to the ground. The sparks are very strong from small wires attached to the free end of the secondary more so than from thick wires. When a coil was connected to the free secondary end the vibration could not be well established, evidently the coil was "out of tune" and by its capacity and inductance interfered with the free vibration of the secondary.
 
The sparks went from the gap-box to the ground though the box was well insulated; there is danger of inflaming the building by this or by the secondary sparks following the wooden structure. The experiments were continued with 7500 volts as yesterday but the working was unsatisfactory. This showed finally that yesterday one of the jars in one set was bad and there was only one set acting, the other set being short circuited; that is why an e.m.f. of 7500 volts was sufficient yesterday.
 
The Westinghouse transformer gains in e.m.f. as jars are put on, the maximum rise seems still remote, this argues well for the economy of the transformer. The incandescent lamps are all destroyed in consequence of the intense secondary vibration, the filaments being broken by electrostatic attraction towards the glass. Lamps were spoiled at a distance of 40 feet from the secondary free terminal! This action is likely to give trouble in future experiments. A curious observation is that all horses shy.
 
It is due to sound or possibly to current action through the ground to which horses are highly sensitive either owing to greater susceptibility of the nerves or perhaps only because of the iron shoe establishing good ground connection. I am not quite certain that the secondary vibration is fundamental although for a lower or higher tone it is too powerful. The external gaps used in some trials seem to improve the action somewhat in rendering the discharges of the primary more sudden. If time should permit the vibration will be investigated by a rotating mirror to be prepared.
 
Tesla demonstrated several single-pole lamps which were connected to the secondary, describing the famous brush-discharge tube and expressing the opinion that it might find application in telegraphy. He noted that high frequency current readily passes through slightly rarefied gas and suggested that this might be used for driving motors and lamps at considerable distance from the source, the high-frequency resonant transformer being an important component of such a system.
 
This invention was his most "sensitive device" and it could be considered as a forerunner of the three-electrode tubes which could be used to amplify and rectify the signals. He designed different bulbs to investigate this phenomena, and it was many years before the invention of the "Audion" (or also known as triode) in 1906 by Lee de Forest. Tesla's three-electrode tubes are described in the article "Pioneer Radio Engineer Gives Views On Power" - New York Herald Tribune - September 11, 1932:
 
"The chief object of employing very short waves is to provide an increased number of channels required to satisfy the ever-growing demand for wireless appliances. But this is only because the transmitting and receiving apparatus, as generally employed, is ill-conceived and not well adapted for selection. The transmitter generates several systems of waves, all of which, except one, are useless. As a consequence, only an infinitesimal amount of energy reaches the receiver and dependence is placed on extreme amplification, which can be easily affected by the use of the so-called three-electrode tubes. This invention has been credited to others, but as a matter of fact, it was brought out by me in 1892, the principle being described and illustrated in my lecture before the Franklin Institute and National Electric Light Association (Experiments with Alternate Currents of High Potential and High Frequency). In my original device I put around the incandescent filament a conducting member, which I called a "sieve." This device is connected to a wire leading outside of the bulb and serves to modify the stream of particles projected from the filament according to the charge imparted to it. In this manner a new kind of detector, rectifier and amplifier was provided. Many forms of tubes on this principle were constructed by me and various interesting effects obtained by their means shown to visitors in my laboratory from 1893 to 1899, when I undertook the erection of an experimental world-system wireless plant at Colorado Springs".
 

A sieve can be observed around the incandescent filament.
 
The true wireless:
 
"My confidence that a signal could be easily flashed around the globe was strengthened thru the discovery of the "rotating brush," a wonderful phenomenon which I have fully described in my address before the Institution of Electrical Engineers, London, in 1892 (Experiments with Alternate Currents of High Potential and High Frequency), and which is illustrated in Fig. 9. This is undoubtedly the most delicate wireless detector known, but for a long time it was hard to produce and to maintain in the sensitive state. These difficulties do not exist now and I am looking to valuable applications of this device, particularly in connection with the high-speed photographic method, which I suggested, in wireless, as well as in wire, transmission."

The Problem of Increasing Human Energy: With Special Reference to the Harnessing of the Sun’s Energy. by Nikola Tesla - Century Illustrated Magazine - June 1900
 
When I advanced this system of telegraphy, my mind was dominated by the idea of effecting communication to any distance through the earth or environing medium, the practical consummation of which I considered of transcendent importance, chiefly on account of the moral effect which it could not fail to produce universally. As the first effort to this end I proposed at that time, to employ relay-stations with tuned circuits, in the hope of making thus practicable signaling over vast distances, even with apparatus of very moderate power then at my command. I was confident, however, that with properly designed machinery signals could be transmitted to any point of the globe, no matter what the distance, without the necessity of using such intermediate stations. I gained this conviction through the discovery of a singular electrical phenomenon, which I described early in 1892, in lectures I delivered before some scientific societies abroad, and which I have called a "rotating brush." This is a bundle of light which is formed, under certain conditions, in a vacuum-bulb, and which is of a sensitiveness to magnetic and electric influences bordering, so to speak, on the supernatural. This light-bundle is rapidly rotated by the earth's magnetism as many as twenty thousand times pre second, the rotation in these parts being opposite to what it would be in the southern hemisphere, while in the region of the magnetic equator it should not rotate at all. In its most sensitive state, which is difficult to obtain, it is responsive to electric or magnetic influences to an incredible degree. The mere stiffening of the muscles of the arm and consequent slight electrical change in the body of an observer standing at some distance from it, will perceptibly affect it. When in this highly sensitive state it is capable of indicating the slightest magnetic and electric changes taking place in the earth. The observation of this wonderful phenomenon impressed me strongly that communication at any distance could be easily effected by its means, provided that apparatus could be perfected capable of producing an electric or magnetic change of state, however small, in the terrestrial globe or environing medium.
 

Stationary waves & the wireless energy experiments

In July 3, 1899 the independence day festivities included the plan of a gigantic display of pyrotechnics on the Summit of Pike's Peak. The officials of the town had brought 35,000 pounds of powder flares for the summit in hopes that the red, white and blue flames would be visible as far away as Cheyenne, Wyoming. Unfortunately the weather didn't want for this to happend and a big and dark storm struck the region and the festivities were canceled, but in this case it represented a good occasion for Tesla to develop his electrical experiments about the earth resonance that he was planning. It was in this occasion which Tesla discovered for first time the existence of stationary waves within the earth during the massive storm. Tesla quickly prepared his instruments during the formation of the storm. As a result of his experiments he stated:
 
“It was on the third of July–the date I shall never forget–when I obtained the first decisive experimental evidence of a truth of overwhelming importance for the advancement of humanity. A dense mass of strongly charged clouds gathered in the west and towards the evening a violent storm broke loose which, after spending its fury in the mountains, was driven away with great velocity over the plains. Heavy and long persisting arcs formed almost in regular time intervals. My observations were now greatly facilitated and rendered more accurate by the experiences already gained. I was able to handle my instruments quickly and I was prepared. The recording apparatus being properly adjusted, its indications became fainter and fainter with the increasing distance of the storm until they ceased altogether. I was watching in eager expectation. Surely enough, in a little while the indications again began, grew stronger and stronger and, after passing thru a maximum, gradually decreased and ceased once more. Many times, in regularly recurring intervals, the same actions were repeated until the storm, which, as evident from simple computations, was moving with nearly constant speed, had retreated to a distance of about three hundred kilometers. Nor did these strange actions stop then, but continued to manifest themselves with undiminished force. Subsequently, similar observations were also made by my assistant, Mr. Fritz Lowenstein, and shortly afterwards several admirable opportunities presented themselves which brought out still more forcibly and unmistakably, the true nature of the wonderful phenomenon. No doubt whatever remained: I was observing stationary waves.”
 
With this results Tesla believed that the earth could react as a body of finite dimensions and for this reason it could resonate. The disturbance of the lightning created waves that would be detected by any reciever with the same strenght as they passed by like if the earth acted as an infinite conductor. When the waves that Tesla measured spread out and then were reflected and superimposed, they formed nodes where they were much stronger than elsewhere. The simple fact that the waves could be reflected proved that a resonant condition could be produced if a powerful signal was in tune with the planet. The waves detected by Tesla in the lighting storm experiment were 25 to 75 kilometers long.
 
This phenomena convinced the inventor not only that the wireless transmission of telegraphic messages was possible but it could also transmit unlimited amounts of power wirelesly to any point of the surface of the planet. After few years of those experiments Tesla wrote an important article in the Century Magazine:

 
"Stationary waves in the earth mean something more than mere telegraphy without wires to any distance. They will enable us to attain many important specific results impossible otherwise. For instance, by their use we may produce at will, from a sending-station, an electrical effect in any particular region of the globe; we may determine the relative position or course of a moving object such as a vessel at sea, the distance traversed by the same, or its speed; or we may send over the earth a wave of electricity traveling at any rate we desire, from the pace of a turtle up to lightning speed."
 
During the next few months Tesla dedicated so much attention to his experiments.Robert Underwood Johnson was a close friend of Tesla's and he once wrote about the great inventor:
 
"Common people must have rest like machinery but the great old Nick - the Busy One- see him go 150 hours without food or drink. Why he can invent with his hands tied behind his back!"
 
The inventor conducted many of his experiments at night, lighting up the darkness of the air of the dry air with his misterious electrical discharges.
 
In a few occasions the experiments would start small fires in his lab and. Once, he was even trapped in a barrage of electric streamers and he had to crawl on his belly for safety to avoid the hot flames and inhalation of smoke, but these were far the most dramatic or dangerous experiments.
 
During mid autuum Tesla needed another assistant for his most magnificent experimentof creating lightning effects because his head assistant, Fritz Lowenstein, was away in Germany because he had some important family matter.
 
Tesla and Czito produced the largest display of man-made lightning ever developed and for this reason they had to protect their ears using cotton balls and they used rubber soled shoes on their feet for isolation to avoid the risk of electrocution in some level. They set cold lamps distributed around the area, and when everything was ready, Tesla gave the order to Czito to close the switch and hold the system activated until he would recieve the other signal to open it again. When the switch was closed the earth shook with the intensity of the mighty apparatus operating in the undamped mode. While some horses were grazing calmly a half mile away, suddenly rose on hind legs andstarted running frantically in all directions probablly because they were spooked by minute shocks received thought their hooves.

 
According to Hunt and Draper, one pair of Tesla biographers:
 
"The crackling and snap repeated and then came a tremendous upsurge of sound as the power built up. There was a crescendo of vicious snaps above. The noises became machine-gun staccato, then roared to artillery intensity. Ghostly sparks danced a macabre routine all over the laboratory. There was a smell of sulfur that might be coming from hell itself. A weird blue light spread all over the room. Flames began to jump from the ball at the top of the mast- first a few feet long- then longer and brighter- thicker, bluer. More emanations until they reached rod like proportions thick as an arm and with a length of over 130 feet. The heavens reverberated with a terrific thunder that could be heard 15 miles over the ridge to Cripple Creek."

On the evening of the experiment, each piece of equipment was first carefully checked. Then Tesla alerted his mechanic, Czito, to open the switch for only one second. The secondary coil began to sparkle and crack and an eerie blue corona formed in the air around it. Satisfied with the result, Tesla ordered Czito to close the switch until told to cease. Huge arcs of blue electricity snaked up and down the center coil and bolts of man-made lightning  of 135 feet in length shot out from the mast atop the station andproducing thunder heard 15 miles distant. When the terrific force suddenly fell in silent and the power was gone, Tesla quickly called the Colorado Springs Electric Company, demanding them to restore the power to find if he was the responsible of destroying the generator, causing it to erupt in flames. Tesla pulled so many amperes that he burned out the municipal generator. The largest generator of that side of the Mississipi was not working and during a short time Colorado Springs was engulfed in darkness. Fortunately for the town they had another generator to replace it, but company officials denied to Tesla the access to electricity with the condition of repairing the original generator at his own expense. And the generator was working again in only a few short days.

Tesla's Views on Electricity and the War - The Electrical Experimenter - August, 1917
 
"The Colorado tests of 1898-1900. Wonderful were the results there obtained, both those anticipated as well as those unexpected. As an example of what has been done with several hundred kilowatts of high frequency energy liberated, it was found that the dynamos in a power house six miles away were repeatedly burned out, due to the powerful high frequency currents set up in them, and which caused heavy sparks to jump thru the windings and destroy the insulation! The lightning arresters in the power house showed a stream of blue-white sparks passing between the metal plates to the earth connection. I could walk on the sand (ordinarily considered a very good insulator) several hundred feet from my large high frequency oscillator, and sparks jumped from my shoes! At such distances all in candescent lamps glowed by wireless power, and banks of lamp, connected to a few turns of wire arranged in a coil on the ground, were lighted to full brilliancy. The effect on metallic objects at considerable distances was really remarkable."
 
If the magnifyer was powered at full, it could be possible to appreciate the lightning rods 12 miles away bridged by small but continuous arcs.
 
His diary is full of details however the results of his experiments are not clear. For exemple, it might be impossible to know if the inventor transmitted wireless power at Pikes Peak.
 
There are some reports that he did transmit a signal several miles powerful enough to illuminate vacuum tubes planted in the ground. But this can be attributed to conductive properties in the ground at Colorado Springs.
 
Another approach pursued by Tesla was to transmit extra-low-frequency signals through the space between the surface of the earth and the ionosphere. Tesla calculated that the resonant frequency of this area was approximately 8-hertz. It was not until the 1950s that this idea was taken seriously and researchers were surprised to discover that the resonant frequency of this space was indeed in the range of 8-hertz.
 
In fact there exist different informations on what this frequency is. Some say 150 kHz, which would be at the upper range of the Colorado Springs transmitter. Others give frequencies considerably lower, 11.78 cycles, 6.8 cycles, frequencies Tesla's transmitter may have achieved harmonically. With reinforcement from the earth resonance, the power would actually increase in the process of transmission.
 
A third approach for wireless power transmission was to transmit electrical power to the area 80-kilometers above the earth known as the ionosphere.
 
Tesla speculated that his region of the atmosphere would be highly conductive and again his suspicions were correct. What he needed was the technical means to send electrical power to such a high altitude.
 
Tesla described one experiment as a square wire loop 50 feet on a side that was laid out on the ground, 100 feet from the oscillator. Three large incandescent bulbs in series in the loop and a tuning capacitor shunted across the bulbs. The bulbs were lit to full brightness when the oscillator was operated at 5% of power.
 

 Can Radio Ignite Balloons? - by Nikola Tesla - Electrical Experimenter - October 1, 1919

Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers
 

Experiment to illustrate an inductive effect of an electrical oscillator of great power.
 
Caption in Century Magazine, June 1900, reads:
 
"The photograph shows three ordinary incandescent lamps lighted to full candle-power by currents induced in a local loop consisting of a single wire forming a square of fifty feet each side, which includes the lamps, and which is at a distance of one hundred feet from the primary circuit energized by the oscillator."

The Problem of Increasing Human Energy - Century Illustrated Magazine - June 1900:
 
The photograph shows three ordinary incandescent lamps lighted to full candle-power by currents induced in a local loop consisting of a single wire forming a square of fifty feet each side, which includes the lamps, and which is at a distance of one hundred feet from the primary circuit energized by the oscillator. The loop likewise includes an electrical condenser, and is exactly attuned to the vibrations of the oscillator, which is worked at less than five per cent. of its total capacity.
 
 
Probablly the most complex experiment with broadcast power was the lighting of 200 light bulbs of 50-watt (a bank of 10,000 watts worth of incandescent bulbs) with electricity circulating through the ground. He accoplished this feat wirelessly without any wire connections at a distance of 26 miles by the transmission of about 10,000 watts without wires from his laboratory. With such succesfull results he claimed that it should be possible to send energy at any distance and anywhere on the globe.

Despite this awsome results, the range of the transmission wasn't great enough for the power distribution. In various later articles, he said that it might be possible with bigger transmitters with the appropiate conditions.
 
The most important reason why Tesla went to Colorado was to test his designs on the wireless signal transmitter. He said that he would build a bigger transmitter in New York that could reach Paris even since he was developing his experiments in Colorado.
 
He used his special detectors to be able to receive impulses from the Magnifying Transmitter at a distance of 600 miles. In that moment it was the greatest achivement compared with any other inventors which were investigating on this subject.
 
In his autobiography "My inventions" by Nikola Tesla - Electrical Experimenter - February, June and October 1919, he states:
 
"When in 1900 I obtained powerful discharges of 100 feet (in the Colorado Springs laboratory) and flashed a current around the globe, I was reminded of the first tiny spark I observed in my Grand St. laboratory and was thrilled by sensations akin to those I felt when I discovered the rotating magnetic field."
 
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. However 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 studies on very low frequency oscillations which does hint at possibilities of remarkable phenomena involving resonance of the Earth’s structure.
 
Tesla applied for patent for the far more refined magnifying transmitter shown at the opening of this chapter, a patent that was not granted until a dozen years later. In this patent he no longer speaks of energy broadcast through the upper strata of the atmosphere but of a grounded resonant circuit. Tesla predicted that his magnifying transmitter would prove most important and valuable to future generations, that it would bring about an industrial revolution and make possible great humanitarian achievements.
 
Assuming that Tesla’s theory of earth conduction was wrong, it may be difficult to believe that so much power could be radiated from the oscillator used by Tesla with its 200-foot mast to act as an antenna but it in fact it could be possible knowing that the amount of power radiated by an aerial is equal to the square of the antenna current times the radiation resistance of the antenna. At 150 KHz, a 200-foot antenna would have a radiation resistance of only about two ohms, which is not very good for an antenna. Anyway, this extremely high current developed by the Magnifying Transmitter could provide some evidence to believe that great quantities of power could be transmitted according to Tesla's experience, at least in considerable distances as observed in his experiments. There were other factors like the advantage when using low frequencies and short antennas since these configurations could provide strong ground wave radiation.
 
Today the efficient near-field power transmission is quite possible but it has a range similar to the size of the antenna. If the antenna has to be this big, you may as well run a wire in most cases.
 
Far-field power transmission is possible if the transmitting antenna is many times the wavelength. This practically needs a laser or microwave transmitter. Both of these are far beyond the technology available to Tesla.
 
The inverse square law ultimately limits the range of free-space transmission.
 
In some occasion Tesla stated that he was also studying the electrical properties of the rarefied mountain air to see if would be possible to use his system to transmit power though the atmosphere. The details of such experiments are uknown but they may have involved high-flying balloons, which Tesla said he used for some experiments. When Tesla returned from Colorado, he said that aerial power transmission would definitely work on an industrial scale.
 
In 1917 during a speech before the American Institute of Electrical Engineers Tesla said that while in C/S his large oscillator once created a dense cloud of water vapor inside of the laboratory building. He also speculated that properly designed plants might be installed in arid regions to draw in water for irrigation. By the way, the entire speech is reprinted in the book Tesla said (See page 188).
 
Tesla's acceptance speech on receiving the Edison Medal, May 18, 1917:
 
"In Colorado I succeeded one day in precipitating a dense fog. There was a mist outside, but when I turned on the current the cloud in the laboratory became so dense that when the hand was held only a few inches from the face it could not be seen. I am positive in my conviction that we can erect a plant of proper design in an arid region, work it according to certain observations and rules, and by its means draw from the ocean unlimited amounts of water for irrigation and power purposes. If I do not live to carry it out, somebody else will, but I feel sure that I am right."
 

 
Tesla's Trick Photography. This widely publicized photo, was explained by Tesla as a dual exposure. Obviously anyone sitting within such electrical activity would be killed immediatly.
 
 
 
Note to Fig. ?. This photograph is showing the coil creating an alternative movement of electricity from the earth into a large reservoir and back at a rate of one hundred thousand alternations per second. The adjustments are such that the reservoir is filled full and bursts at each alternation just at the moment when the electrical pressure reaches the maximum. The discharge escapes with a deafening noise, striking an unconnected coil twenty-two feet away, and creating such a commotion of electricity in the earth that sparks an inch long can be drawn from a water main at a distance of three hundred feet from the laboratory.
 

 
Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers
 
A photograph taken in Colorado Springs, showing the general way in which Tesla sometimes obtained two oscillations. The picture shows a large ball which formed the terminal of the transmitting circuit wound on a frame running around the laboratory, which is seen in the background, and which was used as one element of the complex transmitter. As the other element he would use a second coil of which he had a considerable number, and one of which is shown in the photograph to the left of the observer, at a distance of something like 20 or 25 feet from the ball. When employing the apparatus in accordance with the invention described in his patent US723,188 - Method of Signaling - Mar. 17, 1903 application a coil, as the one illustrated, would be connected to a terminal, such as the ball shown, with one of its ends, while the other end was grounded or, as the case may be, connected to the ground through a condenser. When the transmitter was set at work and the discharge took place, both of the systems would vibrate, each its own period, and thus two vibrations of suitable frequency were passed into the ground, and were used to excite two receiver circuits, each tuned to one of them. This method was also used in obtaining more then two oscillations.
 
The rough coil is co-ordinated oscillator (50,000 periods) with the basic frequency. The two larger vertical coils on the double and the remaining on multiple basic frequency. A small coil co-ordinated with 26 subject basic frequency likewise strongly one excited.
 
The Problem of Increasing Human Energy - Century Illustrated Magazine - June 1900:
 
The picture shows a number of coils, differently attuned and responding to the vibrations transmitted to them through the earth from an electrical oscillator. The large coil on the right, discharging strongly, is tuned to the fundamental vibration, which is fifty thousand per second; the two larger vertical coils to twice that number; the smaller white wire coil to four times that number, and the remaining small coils to higher tones. The vibrations produced by the oscillator were so intense that they affected perceptibly a small coil tuned to the twenty-sixth higher tone.
 
A problem in harmonics on Tesla placed a number of inductance coils within the large high frequency coil as shown each coil resonated or became attuned to a certain harmonic of the fundamental oscilation.
 

Courtesy of Tesla Collection - www.nikolateslalegend.com/news-papers
 
---
 
Here is a photo from Colorado Springs, Colorado (in 1899), illustrating the capacity of the oscillator to create electricity of millions of volts and a frequency of 100,000 alternations per second.
 
The Problem of Increasing Human Energy - Century Illustrated Magazine - June 1900:
 
"Here is a photo from Colorado Springs, Colorado (in 1899), illustrating the capacity of the oscillator to create electricity of millions of volts and a frequency of 100,000 alternations per second.
 
The ball shown in the photograph, covered with a polished metallic coating of twenty square feet of surface, represents a large reservoir of electricity, and the inverted tin pan underneath, with a sharp rim, a big opening through which the electricity can escape before filling the reservoir. The quantity of electricity set in movement is so great that, although most of it escapes through the rim of the pan or opening provided, the ball or reservoir is nevertheless alternately emptied and filled to over-flowing (as is evident from the discharge escaping on the top of the ball) one hundred and fifty thousand times per second".
 

 Burning the nitrogen of the atmosphere.
 
This result is produced by the discharge of an electrical oscillator giving twelve million volts. The electrical pressure, alternating one hundred thousand times per second, excites the normally inert nitrogen, causing it to combine with the oxygen. The flame-like discharge shown in the photograph measures sixty-five feet across.
 

 
Symmetrical discharges at the additionally tuned coil, where the discharges are stopped from streaming to the roof of the building.
 
View of extra coil in action. Wires slightly inclined to the ground, to prevent discharge from going to the roof, were fastened at small distances to a brass ring on top of the coil. Thus a great ammount of streamers were produced and they were necesarely weaker individually.
 


Shown is the extra coil discharging from a brass ring at its top to which thin wires, pointing upward, are fastened. The sparks pass upward to a metal hood fastened to the base of the tower. When operating in this fashion the coil produces the effect of a hot furnace, creating a strong current of air through the open roof. 1899.
 

Photographic view of an experiment to illustrate an effect of an electrical oscillator delivering energy at a rate of seventy-five thousand horse-power
 
The Problem of Increasing Human Energy - Century Illustrated Magazine - June 1900:
 
The discharge, creating a strong draft owing to the heating of the air, is carried upward through the open roof of the building. The greatest width across is nearly seventy feet. The pressure is over twelve million volts, and the current alternates one hundred and thirty thousand times per second.
 

 Experiment to illustrate the supplying of electrical energy through a single wire without return.
 
Courtesy of Tesla Collection - https://www.nikolateslalegend.com/news-papers
 
 
Note to Fig. ?. — An ordinary incandescent lamp lighted by the current passing from the "extra coil" to the structure of iron pipes, the lower end of the latter beeing connected to the ground plate. Is lighted by electrical vibrations conveyed to it through the coil from an electrical oscillator, which is worked only to one fifth of one per cent of its full capacity.
 

 Discharge between a ball of 80 cm of diam and the ground plate

A coil outside the laboratory with the lower end connected to the ground and the upper end free. The lamp is lighted by the current induced in three turns of wire wound around the lower end of the coil.

The Problem of Increasing Human Energy - Century Illustrated Magazine - June 1900:
 
The coil shown in the photograph has its lower end or terminal connected to the ground, and is exactly attuned to the vibrations of a distant electrical oscillator. The lamp lighted is an independent wire loop, energized by induction from the coil excited by the electrical vibrations transmitted to it through the ground from the oscillator, which is worked only to five per cent. of its full capacity.
 

Tesla coil in one experiment of many conducted in Colorado Springs: This is a grounded tuned coil in resonance with a nearby transmitter; light is glowing near the bottom.

Talking with the planets
 
In July of 1899, while tracking lightning storms alone  with his magnifying transmitter in his Colorado Springs laboratory, Tesla observed a series of unusual rhythmic signals which he described as "counting codes." Having just detected cosmic radio signals for the first time and after ruling out solar and terrestrial causes, Tesla concluded that the signals must be from another planet and he suggested that it could be some attempt of communications from an intelligent life-form on either Venus or Mars.
 
Scientists published a study in 1996 replicating Tesla’s experiment and showing that the signal was in fact caused by the moon Io passing through Jupiter’s magnetic field. An alternative explanation is that Tesla may have heard Marconi's wireless telegraphy demonstrations in Europe.
 
Letter to George Scherff by Nikola Tesla - July 4, 1899:
 
"We are getting messages from the clouds one hundred miles away, possibly many  times that distance. Do not leak it to the reporters."
 
 
Tesla was asked by the Red Cross to predict man's greatest possible achievement over the next century. The letter below was his reply (Source: Tesla Society; Image: Tesla at work, via):
 

 
Nikola Tesla - Christmas 1900:
 
To the American Red Cross, New York City.
 
The retrospect is glorious, the prospect is inspiring: Much might be said of both. But one idea dominates my mind. This — my best, my dearest — is for your noble cause.
 
I have observed electrical actions, which have appeared inexplicable. Faint and uncertain though they were, they have given me a deep conviction and foreknowledge, that ere long all human beings on this globe, as one, will turn their eyes to the firmament above, with feelings of love and reverence, thrilled by the glad news: "Brethren! We have a message from another world, unknown and remote. It reads: one… two… three…"
 
 
The problem of increasing human energy - The Century Illustrated Magazine - Nikola Tesla, June 1900 - Pp 175 - 211 (see P. 209):
 
"My measurements and calculations have shown that it is perfectly practicable to produce on our globe, by the use of these principles, an electrical movement of such magnitude that, without the slightest doubt, its effect will be perceptible on so me of our nearer planets, as Venus and Mars. Thus, from mere possibility, interplanetary communication  has entered the stage of probability"
 
"I recognized that an efficient apparatus for, the production of powerful electrical oscillations, as was needed for that specific purpose, was the key to the solution of other most important electrical and, in fact, human problems. Not only was communication, to any distance, without wires possible by its means, but, likewise, the transmission of energy in great amounts, the burning of the atmospheric nitrogen, the production of an efficient illuminant, and many other results of inestimable scientific and industrial value. Finally, however, I had the satisfaction of accomplishing the task undertaken by the use of a new principle, the virtue of which is based on the marvelous properties of the electrical condenser. One of these is that it can discharge or explode its stored energy in an inconceivably short time. Owing to this it is unequaled in explosive violence. The explosion of dynamite is only the breath of a consumptive compared with its discharge. It is the means of producing the strongest current, the highest electrical pressure, the greatest commotion in the medium. Another of its properties, equally valuable, is that its discharge may vibrate at any rate desired up to many millions per second".
 
 
Some planet affected his machine - New York Sun - January 3, 1901:
 
"Movements on instrument repeated  many  times.  Concludes it to be a  message from  another planet."
 
Letter to the editor of the New York Sun - January 9, 1901:
 
"I did not state that I had obtained a message from Mars, I only expressed my conviction that the disturbances that I obtained were of planetary origin"
 
Talking with planets - Collier's weekly - February 9, 1901 - Pp. 4-5 (reprinted as Chapter XVI - Electrical comunications with planets - Polyphase Electric Currents and Alternate-Current Motors - by Silvanus P.Thompson - Volume 4 of The Library of Electrical Science, Collier and Son, NewYork - 1902 - pp. 225-235):
 
"As I was improving my machines for the production of intense electrical actions, I was also perfecting the means for observing feeble efforts. One of the most interesting results, and also one of great practical importance, was the development of certain contrivances for indicating at a distance of many hundred miles an approaching storm, its direction, speed and distance traveled.
 
It was in carrying on this work that for the first time I discovered those mysterious effects which have elicited such unusual interest. I had perfected the apparatus referred to so far that from my laboratory in the Colorado mountains I could feel the pulse of the globe, as it were, noting every electrical change that occurred within a radius of eleven hundred miles.
 
I can never forget the first sensations I experienced when it dawned upon me that I had observed something possibly of incalculable consequences to mankind.
 
Ifelt as though I were present at the birth of a new knowledge or the revelation of a great truth. My first observations positively terrified me, as there was present in them something mysterious, not to say supernatural, and I was alone in my laboratory at night; but at that time the idea of these disturbances being intelligently controlled signals did not yet present itself to me.
 
The changes I noted were taking place periodically nd with such a clear suggestion of number and order that they were not traceable to any cause known to me. I was familiar, of course, with such electrical disturbances as are produced by the sun, Aurora Borealis, and earth currents, and I was as sure as I could be of any fact that these variations were due to none of these causes.
 
The nature of my experiments precluded the possibility of the changes being produced by atmospheric disturbances, as has been rashly asserted by some. It was some time afterward when the thought flashed upon my mind that the disturbances I had observed might be due to an intelligent control.
 
Although I could not decipher their meaning, it was impossible for me to think of them as having been entirely accidental.
 
The feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another. A purpose was behind these electrical signals.”
 
 
Nikola Tesla, 1907:
 
"I refer to the strange electrical disturbances, the discovery which I announced six year ago. At that time I was only certain that they were of planetary origin. Now, after mature thought and study, I have come to the positive conclusion that they must emanate from Mars"
 
 
Nikola Tesla, 1909:
 
"To besure, we have no absolute proof that Marsisinhabited... Personally, I base my faith on the feeble planetary electrical disturbances which I discovered in the summer of 1899, and which, according to my investigations, could not have originated from the sun, the moon, or Venus.  Further studysince has satisfied me they must have emanated from Mars."
 
Nikola Tesla, 1919:
 
"During my experiments there [Colorado Springs, 1899], Mars was at a relatively small distance fromus and, in that dry and rare fied air, Venus appeared so large and bright that it might have been mistaken for one of those military signaling lights... I came to the conclusion that [Mars] was sufficient to exert a noticeable influence on a delicate receiver of the kind I was perfecting... my ear barely caught signals coming in regular succession which could not have been produced on earth, caused  by any solar or lunar action or by the influence of Venus, and the possibility that they might have come from Mars flashed upon my mind."
 
Nikola Tesla, 1921:
 
"The arrangement of my receiving apparatus and the character of the disturbances recorded precluded the possibility of their being of terrestrial origin, and I also eliminated the influence of the sun, moon and Venus. As I announced, the signals consisted in a regular repetition of numbers, and subsequent study convinced me that they must have emanated from Mars, this planet having been just then close to the earth."
 
 
Transmitter configurations
 
http://www.frankgermano.net/nikolatesla2.htm - (lost source)
http://www.tuks.nl/Mirror/frankgermano_net/nikolatesla2.htm
http://www.teslaradio.com/pages/wardenclyffe.htm
 
If it is desired to construct a coil for the express purpose of performing high frequency and wireless experiments or 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)
 

A Tesla high-tension induction coil

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.
 
http://www.tfcbooks.com/mall/more/301-ntww.htm
 
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.
 
The coupling between the transmitter's two elevated terminals is by electrostatic induction or, in the case of a high-power transmitter, by true electrical conduction through plasma. There is also some degree of inductive magnetic coupling between the two resonators. The type-two transmitter is particularly well suited for the excitation of earth resonance modes. It's interesting to see that in the related patent US787,412 - Art of Transmitting Electrical Energy Through the Natural Mediums - April 18, 1905 Tesla shows a form of receiver that does not involve a resonator coil.
 
 
http://www.frankgermano.net/nikolatesla2.htm - (lost source)
http://www.tuks.nl/Mirror/frankgermano_net/nikolatesla2.htm
http://www.teslaradio.com/pages/wardenclyffe.htm
 
In 1899 Tesla established the Colorado Springs experimental station. The apparatus he assembled there served as a test bed with which to evaluate the type-two and type-one transmitter configurations described above, along with variations of the same. Tesla settled upon the six arrangements shown in the Colorado Springs Notes on pages 190 and 191, and also a reproduction of Tesla’s original lab note on page 200.
 

Figure ?. One of the transmitter configurations illustrated in the Colorado Springs Notes (Sept. 19, 1899 - figure 5, p. 191/200).
 

Figure ?. This is the Colorado Springs configuration that was incorporated into the initial Wardenclyffe design (CSN - Sept. 19, 1899 - figure 6, p. 191/200)
 
Tesla’s own sketches of the 6 transmitter configurations developed at the Colorado Spring’s experimental station (C/S #s 1, 2, 3, 4, 5 & 6). Tesla’s rendering the last of these at a slightly larger scale than the rest reflects his enthusiasm for the design. (Colorado Springs Notes, pp. 190-191, 200)
 
Figure 1 is a type-one transmitter and 2 through 4 are modifications thereof; 5 and 6 are type-two transmitters. Tesla felt arrangement #6 was the most promising. It shows up with slight variations at a number of places in the Colorado Springs Notes, most significantly on pages 191, 200, 197 and 170 (see also pages 161, 162, 174, 177 and 184). In the corresponding text on page 191 Tesla writes, "In Fig. 5. & 6. it is found best to make [the] extra coil 3/4 wave length and the secondary 1/4 for obvious reasons." This two-coil/two-ground configuration was incorporated into the initial Wardenclyffe design. On May 29, 1901 note Tesla wrote of the design,
 
"The length of conductors in the free system (equivalent to the 3/4 lambda extra coil in figure 5/6 CSN p. 191/200) should be lambda/4, and the length of the discharging circuit (equivalent to the 1/4 lambda secondary in figure 5/6) should be 3/4 lambda or n/4 lambda “n” could be very large reflecting the wavelength of the superimposed ELF excitation). Eventually, n being an uneven number."
 

 
This is a basic rendering of the type-two transmitter configuration, the same design as that illustrated in the Colorado Springs Notes (type-two, C/S #6). A receiving circuit is standing out to the right. This general configuration was to be incorporated into the initial Wardenclyffe design, but it was not implemented. (Rare notes from Tesla on Wardenclyffe by Leland Anderson, Electric Spacecraft Journal, Apr./May/June, # 26, 1998; See also “Wardenclyffe and the World System.”)
 
The AND-logic gate patents (US723,188 - Method of Signaling - Mar. 17, 1903 and US725,605 -System of Signaling - Apr. 14, 1903) show a similar arrangement; only the transmitter consists of two electrically driven oscillators tuned to different frequencies instead the single-frequency oscillator-plus-extra coil combination. Also, the transmitter has a common ground. The original application filing date is July 16, 1900 and it is probable that the Wardenclyffe installation, as initially proposed, would have taken on some attributes of this configuration, along with some modifications. For example, each transmitter secondary could be provided with a dedicated ground, and perhaps an independent high voltage power supply as well. Also, it has been suggested that if each transmitter was to be nearly in tune with its partner—say having only a 12 Hz difference in vibration rate—a low-frequency beat tone would be produced, thus introducing an ELF component to the wave complex.

 Drawings from the U.S. AND-logic gate patent METHOD OF SIGNALING, No. 723,188 (improved type-one, C/S #1). Dr. Nikola Complete Patents, p. 409

Tesla’s 1900 patent drawing showing a system for the wireless transmission and reception of electrical energy through the earth’s rarefied upper atmosphere with ground for return. (Transmitter type-one, C/S #1)

 In these set-ups of the Colorado Springs lab. it can be observed an extra spark gap (C1-C2 in the “rare notes” which concerns Wardenclyffe) and a 4th inductor (indicated in blue)
 
Quotes on the wireless experiments:
 
The Problem of Increasing Human Energy: With Special Reference to the Harnessing of the Sun’s Energy - The Century Magazine - June, 1900:
 
"In recent experiments I have discovered two novel facts of importance in this connection.  One of these facts is that an electric current is generated in a wire extending from the ground to a great height by the axial, and probably also by the translatory, movement of the earth.  No appreciable current, however, will flow continuously in the wire unless the electricity is allowed to leak out into the air.  Its escape is greatly facilitated by providing at the elevated end of the wire a conducting terminal of great surface, with many sharp edges or points. We are thus enabled to get a continuous supply of electrical energy by merely supporting a wire at a height, but, unfortunately, the amount of electricity which can be so obtained is small.

The second fact which I have ascertained is that the upper air strata are permanently charged with electricity opposite to that of the earth. So, at least, I have interpreted my observations, from which it appears that the earth, with its adjacent insulating and outer conducting envelope, constitutes a highly charged electrical condenser containing, in all probability, a great amount of electrical energy which might be turned to the uses of man, if it were possible to reach with a wire to great altitudes."
 
Tesla's acceptance speech on receiving the Edison Medal, May 18, 1917
 
"I have learned how to put up a plant that will develop a tension of 100,000,000 volts and handle it with perfect safety. This plant (indicating) was in Colorado. If anybody, who had not been dabbling in these experiments as long as myself, had done such work, he would surely have been killed. In this plant I had the narrowest escape ever. It was a square building, in which there was a coil 52 feet in diameter, about nine feet high. When it was adjusted to resonance, the streamers passed from top to bottom and it was a most beautiful sight. You see, that was about fifteen hundred, perhaps two thousand square feet of streamer surface. To save money I had calculated the dimensions as closely as possible, and the streamers came within six or seven inches from the sides of the building. As boys had been looking through a single window provided in the rear, I nailed it up. For handling the heavy currents, I had a special switch. It was hard to pull, and I had a spring arranged so that I could just touch the handle and it would snap in. I sent one of my assistants down town and was experimenting alone. I threw up the switch and went behind the coil to examine something. While I was there the switch snapped in, when suddenly the whole room was filled with streamers, and I had no way of getting out. I tried to break through the window but in vain as I had no tools, and there was nothing else to do than to throw myself on my stomach and pass under. The primary carried 500,000 volts, and I had to crawl through the narrow place here (pointing) with the streamers going. The nitrous acid was so strong I could hardly breathe. These streamers rapidly oxidize nitrogen because of their enormous surface, which makes up for what they lack in intensity. When I came to the narrow space they closed on my back. I got away and barely managed to open the switch when the building began to burn. I grabbed a fire extinguisher and succeeded in smothering the fire. Then I had enough, I was all in. But now I can operate a plant without any fear of its destruction by fire".
 
Tesla, 75, Predicts New Power Source - New York Times - July 5th, 1931
 
"When and where do you expect to make the official announcement of your new discoveries?" the inventor was asked.
 
These discoveries," he replied, "did not come to me over night, but as the result of intense study and experimentation for nearly thirty-six years. I am naturally anxious to give the facts to the world as soon as possible, but I also wish to present them in a finished form. That may take a few months or a few years.
 
The idea of atomic energy is illusionary but it has taken so powerful a hold on the minds, that although I have preached against it for twenty-five years, there are still some who believe it to be realizable.
 
I have disintegrated atoms in my experiments with a high potential vacuum tube I brought out in 1896, which I consider one of my best inventions. I have operated it with pressures ranging from 4,000,000 to 18,000,000 volts. More recently I have designed an apparatus for 50,000,000 volts which should produce many results of great scientific importance.
 
But as to atomic energy, my experimental observations have shown that the process of disintegration is not accompanied by a liberation of such energy as might be expected from the present theories.
 
And as for the cosmic ray: I called attention to this radiation while investigating Roentgen rays and radioactivity. In 1899 I erected a broadcasting plant at Colorado Springs, the first and only wireless plant in existence at that time, and there confirmed my theory by actual observation. My findings are in disagreement with the theories more recently advanced.
 
I have satisfied myself that the rays are not generated by the formation of new matter in space, a process which would be like water running up hill. According to my observations, they come from all the suns of the universe and in such abundance that the part contributed by our own sun is very insignificant by percentage. Some of these rays are of such terrific power that they can traverse through thousands of miles of solid matter".
 
 
Sources:

⦁    http://en.wikipedia.org/wiki/Colorado_Springs_Notes,_1899%E2%80%931900
⦁    History of Wireless" by T. K. Sarkar,Robert Mailloux,Arthur A. Oliner,M
⦁    http://peswiki.com/energy/PowerPedia:Nikola_Tesla
⦁    http://www.pbs.org/tesla/ll/ll_colspr.html
⦁    http://blog.world-mysteries.com/science/incredible-inventions-of-nikola-tesla/
⦁    http://www.magnetricity.com/Tesla/Tesla_Colorado.php
⦁    http://www.neatorama.com/spotlight/2010/03/04/tesla-master-of-lightning/
⦁    http://www.teslascience.org/archive/archive.htm#Colorado
⦁    http://www.energeticforum.com/renewable-energy/3573-teslas-wireless-electricity-transmission-8.html
⦁    http://www.tfcbooks.com/mall/more/371tcbg.htm
⦁    http://www.magnetricity.com/Tesla/Tesla.php#Gallery
⦁    http://www.moebius-bcn.com/?p=1802
⦁    http://www.pupman.com/listarchives/1995/july/msg00013.html
⦁    http://www.teslasociety.com/mars.pdf
⦁    http://altered-states.net/barry/tesla/
⦁    https://mage00000.blogspot.com/p/blog-page_8.html

 

Other links to check:
⦁    http://www.thedenvereye.com/nikola-tesla-in-colorado-springs/
⦁    http://www.spaceandmotion.com/Physics-Nikola-Tesla-Inventions-Resonance.htm
⦁    https://archive.org/stream/TheLostJournalsOfNikolaTesla/The%20Lost%20Journals%20Of%20Nikola%20Tesla_djvu.txt

 

This article represents the adaptation of original article published on teslaresearch.jimdofree.com.