Nikola Tesla: a study primer

Written for a self-taught reader at undergraduate level. Source tags: [read] from a document in the project folder or in the Investigator's saved files (research/files/); [web] with URL; [memory] recalled, with a confidence level; [calc] computed here and reproduced in example.py. The final verdicts are the arbiter's (arbiter.md); this primer adds no new verdicts. Where I correct an earlier file, it is listed in "Corrections to earlier documents" at the end.

Source gap (repeated from earlier steps, as updated by the arbiter). The folder is rich in readable text: all 30 manifest documents were extracted, including the collected US patents, T. C. Martin's 1894 book of Tesla's lectures, the 1891 lecture, the 1900 Century article, the 1892 "Dissipation" letter, the 1919 "Famous Scientific Illusions" and the compilation Tesla Said (letters and articles 1888-1939). The Investigator added Tesla's Colorado Springs Notes 1899-1900 (1978 edition), the 5 March 1904 Electrical World and Engineer article and the 1916 interview with his patent counsel (Anderson, ed., 1992), so the 1899 storm observation is now read in Tesla's own words. Of the Notes, the 3-4 July 1899 entry was read first; a further read (2026-10-08) added the entries of 24 and 30 July, 6 August, 26 and 28 August and 8 December 1899, the photograph notes of 1-2 January 1900 and the editor's introduction and main commentary. The rest of the Notes is unread. The 1916 interview's Colorado chapter and its Wardenclyffe appendix (the 1922 foreclosure appeal) and the 1904 letters to W. B. Rankine have also been read; the Kerr, Page and Cooper patent opinion mentioned in those letters is not in the scan. Three deep reads were first blocked by an automatic content filter; the retries covered the 1900 Century article pp.15-24 and Free Energy Secrets pp.137-156. The Century pages 1-14 and 25-33 have no separate deep read, though they were read in full from the text layer and are quoted here. Still not seen by anyone in this review: the Allis-Chalmers (Dahlstrand) turbine report, Professor Richards's test log, John Trump's 1943 report on Tesla's papers and the full texts of the exhibits he abstracted (only the FBI file's abstracts are read), Eyring Corp.'s raw coil traces, any "teleforce" apparatus or test record, any output measurement of a "fuelless" or "radiant energy" device, Fritz Lowenstein's own account of his "similar observations", Sutton and Spaniol (1988) and Corum, Corum and Spaniol (1988) on cavity Q, R. Golka's Air Force reports, John B. Flowers's 1925 proposal and any Bureau of Standards reply, a published field measurement from the modern Viziv/CPG tower, and Part 03 of the FBI Vault file. Statements about these rest on the one secondary quotation named in each case.

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1. The idea in one paragraph

Nikola Tesla (1856-1943) built the alternating-current motor and power system the world still uses, and then spent the rest of his life on a larger idea: that the whole earth could be "rung" like a tuned electrical circuit, so that a resonant transmitter at one place would set up standing waves over the planet, and a tuned receiver anywhere could draw power from them, at almost no loss and without wires. He based this on real things he had mastered: electrical resonance (a tuned circuit builds up huge voltages from a small push), the high-frequency, high-voltage "Tesla coil", and an evening in Colorado in July 1899 when his receiver came and went at regular intervals as a thunderstorm moved away, which he read as the nodes and loops of a standing wave in the earth. Around this core sit other claims: that radio-type radiation is a wasteful sideshow to "true conduction", that energy might be drawn from the surrounding medium, that his bladeless disc turbine could reach 80-90 per cent efficiency, and a 1930s "teleforce" beam. Some of this is now standard engineering (resonance, the coil, very-low-frequency signalling around the globe, and the earth-ionosphere cavity really does ring, at about 8 cycles per second). The power-without-loss part fails when the measured losses of the earth and the upper atmosphere are put into the numbers, and the turbine works but at roughly a quarter to a half of ideal-expansion efficiency, against the 80-90 per cent he stated.

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2. What you need to know first

Resonance in an LC circuit, and the quality factor Q. An inductor L (henry, H) and a capacitor C (farad, F) connected together exchange energy back and forth at the resonant frequency f0 = 1 / (2 pi sqrt(L C)) (cycles per second, hertz, Hz). With a resistance R in series, each cycle loses a little energy; the quality factor Q = omega0 L / R (omega0 = 2 pi f0, the angular frequency) measures how many cycles the oscillation survives (energy falls by a factor of about e^(-2 pi) every Q cycles). Driven at resonance by a voltage V_in, the capacitor voltage rises to Q V_in. This is voltage magnification, not power gain: in steady state the source supplies exactly the power the resistance dissipates. Read: any circuits text; Griffiths, Introduction to Electrodynamics, the section on AC circuits is brief, so a circuits text such as Horowitz and Hill, The Art of Electronics, chapter 1, is better. [memory: high]

Waves on a line, and standing waves. A wave of frequency f moving at speed v has wavelength lambda = v / f. Two equal waves travelling in opposite directions add to a standing wave: fixed nodes (zero) and loops (maximum), with nodes half a wavelength apart. If the returning wave is weaker, with amplitude ratio r (0 to 1), the pattern only ripples: maximum / minimum = (1 + r) / (1 - r), the "standing-wave ratio" (SWR). A conductor a quarter of a wavelength long, grounded at one end and open at the other, resonates (the "quarter-wave" rule Tesla uses). Read: any first-year physics text on waves (e.g. Halliday, Resnick and Walker, the chapters on waves). [memory: high]

Decibels. Losses in communication are given in decibels (dB): a power ratio P2/P1 is 10 log10(P2/P1) dB. A loss of 10 dB leaves 1/10 of the power, 20 dB leaves 1/100, 60 dB leaves one millionth. Field amplitude goes as the square root of power, so an amplitude ratio is 20 log10(A2/A1) dB. A loss "per megametre" (dB/Mm; 1 Mm = 1000 km) just multiplies by distance. Physicists sometimes write the same thing with natural logarithms: an amplitude that falls as e^(-x) has lost x nepers (Np), and 1 Np = 20 log10(e) = 8.686 dB. So an attenuation constant of 1e-7 per metre (amplitude falling as e^(-1e-7 d)) is 0.1 Np/Mm = 0.87 dB/Mm. [memory: high]

Energy flow in fields: the Poynting vector and radiation. In Maxwell's theory the power per square metre carried by fields is the Poynting vector S = E x H (E the electric field in volts per metre, H = B / mu0 the magnetic field in amps per metre, B in tesla, mu0 = 4 pi x 10^-7 H/m, "x" the vector cross product). Near an antenna the fields contain a large "near field" that falls as 1/r^3 (electric, like a static dipole) or 1/r^2 and mostly stores energy, sloshing back and forth; far away only the "radiation field" (falling as 1/r) remains and carries energy outward. A real antenna presents a radiation resistance R_rad: the power radiated is I^2 R_rad (I the antenna current, rms), so a short antenna with tiny R_rad radiates little. Read: Griffiths chapters 7 (electrodynamics), 8 (conservation laws, Poynting's theorem), 9 (electromagnetic waves) and 11 (radiation) [memory: high for the 3rd and 4th editions]; J. D. Kraus, Antennas, for radiation resistance.

Skin depth. An alternating current in a conductor of conductivity sigma (siemens per metre, S/m; resistivity rho = 1/sigma in ohm-metres) does not fill it: it is confined to a surface layer of thickness delta = sqrt(2 / (omega mu0 sigma)), which is about 503 sqrt(rho / f) metres. Damp ground (rho about 100 ohm-m) at 250 kHz gives about 10 m. So "current through the earth" at radio frequencies runs in a thin skin of a lossy conductor, not through the whole planet. Read: Griffiths chapter 9 (waves in conductors). [memory: high]

Waveguides, and the earth-ionosphere guide. Two conducting surfaces a distance h apart guide waves between them. The ground and the ionosphere (the electrically conducting upper atmosphere; its lowest layer at night is at about 70-90 km) form such a guide around the whole planet. Very low frequency (VLF, 3-30 kHz) waves travel thousands of kilometres in it, losing roughly 2-3 dB per Mm in daytime [web: https://en.wikipedia.org/wiki/Very_low_frequency]; navies use it to signal submarines worldwide [memory: high]. At the lowest frequencies the whole guide is a resonant cavity: its "Schumann resonances" are at about 7.8, 14.1 and 20.3 Hz, excited by lightning [web: https://en.wikipedia.org/wiki/Schumann_resonances]. Read: J. R. Wait, Electromagnetic Waves in Stratified Media; K. G. Budden, The Waveguide Mode Theory of Wave Propagation; A. P. Nickolaenko and M. Hayakawa, Resonances in the Earth-Ionosphere Cavity (2002) [memory: high for titles].

Two-port networks and S21 (needed for the bifilar coil). A network analyser sends a wave into port 1 and measures what comes out at port 2; the ratio is S21, the "transmission coefficient". For a passive part (no power supply) |S21| cannot exceed 1. A series impedance Z between two ports of impedance Z0 = 50 ohm gives S21 = 2 Z0 / (2 Z0 + Z). Read: D. M. Pozar, Microwave Engineering, the chapter on microwave network analysis. [memory: high]

The second law of thermodynamics (for the "fuelless" claims). No cyclic engine can turn heat from a single reservoir entirely into work (the Kelvin-Planck statement). Between a hot reservoir T_h and a cold one T_c (kelvin), the best possible efficiency is the Carnot value 1 - T_c/T_h. Energy can be harvested from natural gradients (sun, wind, temperature differences, the atmosphere's electric field); not from surroundings in equilibrium. Read: Y. A. Cengel and M. A. Boles, Thermodynamics: An Engineering Approach, the chapters on the second law. [memory: high]

Boundary layers (for the disc turbine). A viscous fluid sticks to a surface and drags it; in the thin "boundary layer" near the surface the velocity changes from the surface's to the stream's. Tesla's turbine uses this drag between steam and closely spaced discs instead of blades. Steam-turbine performance is judged against ideal (isentropic, no-friction) expansion: the ideal steam rate is 2545 / Delta h_s pounds of steam per horsepower-hour, where 2545 Btu = 1 hp for one hour and Delta h_s is the ideal enthalpy (heat content) drop in Btu per pound. The enthalpy and entropy of steam at a given pressure and temperature come from steam tables; the arbiter computed them with IAPWS-IF97, the "Industrial Formulation 1997" of the International Association for the Properties of Water and Steam, the standard set of fitted equations from which modern steam tables are printed. Read: F. M. White, Fluid Mechanics, the chapter on boundary layers; Cengel and Boles on steam power cycles. [memory: high]

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3. The textbook view

3.1 Resonant circuits and the Tesla coil

A Tesla coil is two coupled resonant circuits. The primary (a capacitor C1 discharged through a spark gap into a few turns L1) rings at f = 1/(2 pi sqrt(L1 C1)); the secondary (a long coil L2 whose own distributed capacitance, plus a top terminal, gives C2) is tuned to the same frequency. Energy pumped in each spark builds up in the secondary until losses balance input, and the secondary voltage reaches hundreds of kilovolts to megavolts. All of this is textbook and was in large part shown first by Tesla in 1891-93 [read: Martin 1894; 1891 lecture; memory: high].

Check on Tesla's own "model plant" in US 645,576 (1900): a condenser of "about four one-hundredths of a microfarad" (C = 0.04 uF) charged to "fifty thousand volts" and broken "five thousand times per second", with a primary of about 10,000 cm of inductance (L = 10 uH in modern units; 1 cm of inductance = 1 nH) [read: Complete Patents, PDF pp.356-357, via deep read]. Then f = 1/(2 pi sqrt(10e-6 x 0.04e-6)) = 252 kHz, matching his stated 230-250 kHz [calc, Mathematician and Contrarian]. Each break stores (1/2) C V^2 = 0.5 x 0.04e-6 x (5e4)^2 = 50 J, so 5,000 full breaks a second would be 250 kW; the patent gives no power figure to compare [calc, Contrarian].

3.2 How energy reaches a distant receiver

In mainstream physics there are two regimes:

• Near field (within about a wavelength / 2 pi of the source): large electric and magnetic fields that store energy and return most of it to the source each cycle. They can light a lamp or power a coil a few metres away by coupling. Modern resonant wireless charging (the MIT/WiTricity work, whose patents cite Tesla's US 787,412 [read: research/2026-10-08-google-patents.md]) is this.
• Far field: energy that leaves for good, carried by the Poynting flux S = E x H, falling in intensity as 1/r^2 in open space. Over the earth this energy is confined between ground and ionosphere, so beyond a few hundred km it spreads in two dimensions only, over a band of height h. At great-circle distance d on a sphere of radius a the band has circumference 2 pi a sin(d/a), so the intensity is

S(d) = P0 x 10^(-alpha d / 10) / (2 pi a sin(d/a) h)

where P0 is the power launched, alpha the attenuation in dB per metre, a = 6371 km, h about 70 km. The sin(d/a) factor shrinks again past a quarter of the way round, so the wave refocuses at the antipode (the opposite point of the earth). That focusing is real and is one point where Tesla's intuition about "the region diametrically opposite" was right [memory: medium, Physicist].

The losses are in the guide: currents flowing in the lossy ground (skin depth above) and in the weakly conducting ionosphere. They depend on frequency. At VLF they are about 2-3 dB/Mm by day (less at night) [web, above]. At the Schumann frequencies they are much lower: a measured first-mode Q of about 3.3 [web: https://repository.kulib.kyoto-u.ac.jp/dspace/handle/2433/178586, via the Mathematician's review] corresponds to about 0.2 dB/Mm [calc, example.py step 3], low enough that waves from lightning circle the globe several times and build a standing pattern.

3.3 The earth's own resonances

For an ideal thin shell cavity of radius a, the resonant frequencies are f_n = (c / 2 pi a) sqrt(n(n+1)), n = 1, 2, 3, ..., giving 10.6, 18.4, 26 Hz; the real modes are lower (7.8, 14.1, 20.3 Hz) because the walls conduct imperfectly [calc and memory: high, Mathematician]. The simpler estimate "one wavelength equals the circumference", f = c / (2 pi a) = 7.49 Hz, is close to the first observed mode [calc].

3.4 Electrostatics, corona and the "ether" in 1891-1905

Near a high-voltage terminal at high frequency, air ionises (corona), heats and moves (ion wind); energy is lost to the air. This is measured and is a design limit for power lines [memory: high]. The question of a mechanical "ether" carrying light was open in 1891; Heinrich Hertz had shown in 1887-88 that Maxwell's transverse electromagnetic waves exist, reflect, refract and travel at the speed of light, and radio since then confirms it [memory: high]. In free space Maxwell's equations allow no longitudinal, energy-carrying electromagnetic wave; longitudinal field components exist only near sources, in guides, in plasmas and in surface waves [memory: high].

3.5 The second law, and the disc turbine

A heat engine between T_h = 300 K and a sink at T_c = 77 K has Carnot efficiency 1 - 77/300 = 0.743; keeping the sink cold with a perfect refrigerator costs 0.257 / (77/223) = 0.743 J per joule of work, exactly cancelling [calc, Mathematician]. A disc turbine is a legitimate boundary-layer machine; small modern test rigs measure about 14-35 per cent efficiency (Armstrong 1952: 14 per cent; later machines "between 20 and 35 per cent"; Hoya and Guha 2009: 140 W at 25,000 rpm, about 25 per cent, losses dominated by the nozzle) [read: research/files/hoya-guha-2009-tesla-turbine-test-rig.pdf].

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4. Where Tesla departs

The starting points below are real physics that Tesla understood well, often earlier than others. The departures are the steps where he goes further than the physics, as judged in the arbiter's verdicts.

4.1 Wireless power through the earth (claim 1)

What he observed. The diary entry headed "Colorado Springs, July 4, 1899: Observations made last night" (the night of 3 July) [read: research/files/colorado-springs-notes-1899-1900_djvu.txt, around line 2700]: a rotating coherer receiver "connected to ground and a plate above ground" started to "play" when the storm was 80-100 miles away (distance from the thunder delay); stopped at about 50 miles; then "all of a sudden the instrument began again to play, continuously increasing in strength, although the storm was moving away rapidly"; it ceased, came back half an hour later, and so on, "in intervals nearly of half an hour", with the storm "at a distance greater than 200 miles at least". Between returns he made the relay "more delicate, in fact very considerably so", and later "the spring was tightened on the relay very much". His reading: "It showed clearly the existence of stationary waves, for how could the observations be otherwise explained? ... It would be difficult to believe that they were reflected from the opposite point of the Earth's surface, though it may be possible. But I rather think they are reflected from the point of the cloud where the conducting path began; in this case the point where the lightning struck the ground would be a nodal point." [read]

What he concluded in print. In 1904: "the storm ... had retreated to a distance of about three hundred kilometers ... similar observations were also made by my assistant, Mr. Fritz Lowenstein ... I was observing stationary waves ... Impossible as it seemed, this planet, despite its vast extent, behaved like a conductor of limited dimensions", so that power could be sent "in unlimited amounts, to any terrestrial distance and almost without loss" [read: research/files/tesla-1904-transmission-without-wires.pdf, p.2]. In 1905 the current "travels to the diametrically opposite region ... and rebounding from there, returns to its point of departure with virtually undiminished force", and from many observations "I found their length to vary approximately from twenty-five to seventy kilometres" [read: Tesla Said pp.91, 95]. The loss claim: "a loss not exceeding a small fraction of one per cent in the transmission, even to the greatest distance, twelve thousand miles - to the opposite end of the globe" [read: Tesla Said p.90, page image]. US 787,412 (filed 16 May 1900) states that "the planet behaves like a perfectly smooth or polished conductor of inappreciable resistance ... transmitting slow electrical oscillations without sensible distortion and attenuation", that the frequency "should be smaller than twenty thousand per second", that "the lowest frequency would appear to be six per second", and that a wave train must last "not less than one-twelfth or probably 0.08484 of a second", the time to go to the antipode and back at "about four hundred and seventy-one thousand two hundred and forty kilometers per second" [read: Complete Patents, PDF p.425].

What the diary says six months later. In the photograph notes dated 2 January 1900 (photographs of 17-31 December 1899) Tesla describes "five incandescent lamps lighted - and to much more than normal candle power - on a table in front of the coil", wired in series between the ground and the lower end of a coil whose upper end was "entirely insulated", and writes: "It was astonishing to note ... how much energy can be in this manner conveyed to such a carefully synchronized coil through the ground." Scaling up from the fraction of his supply in use, he estimates "about 40 lamps", or "60 lamps or so" with a specially designed coil. Then: "one of the problems followed up here, that is the establishment of communication with any point of the globe irrespective of distance, is very near its practical solution. The existance of stationary waves proves the feasibility of the project almost beyond any doubt." [read: research/files/colorado-springs-notes-1899-1900_djvu.txt, lines ~18388-18560, printed pp.347-349] For this test Tesla short-circuited the oscillator's own windings, so the coil received the energy through its ground wire. He matched the coil's wire (2,660 ft) to a quarter wavelength at his 93,110 cycles per second (wavelength "very nearly 2 miles") [read: lines 18480-18510]. The Notes give no distance between the exciting ground and the lamp circuit; the editor confirms "Tesla gives no data about the distance" [read: line 22520]. The set-up was in or beside the laboratory. A different set-up the day before (1 January) lit three lamps in a 62 ft square loop of wire on the snow, centred "a little over 60 feet" from the primary loop and not grounded: that is magnetic induction, like a transformer with a very loose coupling [read: lines 18198-18306]. Both are short-range coupling, which is standard physics. The step from them, and from the 3 July stationary waves, to global feasibility is Tesla's inference.

Tesla then estimated the energy involved: the coil's free end (about 162 pF) at about 141,000 V and 93,000 cycles per second gives C V^2 f = 300,000 W "set in movement", of which the lamps would take 1 per cent; he calls it "merely an example" [read: lines 18575-18636; calc checked]. The editor, Marinčić, corrects the physics: that figure is energy circulating in the resonator, and "the active power dissipated in the circuit is much less than this and is inversely proportional to the Q-factor" [read: line 22512-22515]. A resonator with Q of 10 keeps about ten times its per-cycle loss sloshing between the coil's field and its capacitance; the circulating rate is not power that can be sent anywhere. The arbiter's verdict (revision F): as transferable power, Refuted by calculation; as arithmetic on Tesla's own assumptions, consistent.

The lightning-arrester sparks (July-August 1899). Much of Tesla's case that the ground itself carried his waves rests on sparks across the lightning arresters (spark gaps between the incoming power lines and their own ground). On 24 July, with his secondary on an isolated ground plate, sparks still crossed the arresters, and he wrote that "the earth behaves simply as an ordinary conductor and that it will be possible, with powerful apparatus, to produce the stationary waves which I have already observed" [read: Notes lines 5077-5088]. On 26 August, with waves he put at "3-4 miles long" (about 50-60 kHz), the arresters arced heavily; whether his ground connection was a node or a crest was "to be decided by further observations", and he asked himself: "Could the sparks be produced by static induction upon wire through the air and not chiefly by conduction through earth?" [read: lines 7972-8081]. His 6 August "experiments with stationary waves on water pipe" were never written up; the only datum is "Distance from groundplate to End of main exactly 550 feet" [read: lines 6320-6327]. Marinčić judges that standing waves "cannot be significant at these frequencies" for the arrester sparks [read: line 21457-21460]. Arbiter's verdict (revision F): the sparks are Established as local ground-potential differences and induction near a powerful transmitter; as evidence of stationary waves in the earth they are Never properly tested, because Tesla's own alternative was not excluded.

So the diary is not simply the cautious record. Its caution on 3-4 July concerns only where the waves were reflected ("difficult to believe that they were reflected from the opposite point"); by January 1900, before the May 1900 patent filing, it already calls the global project feasible "almost beyond any doubt". What changes in print is the mechanism: the patent filed in May 1900 and the 1904-05 articles make the antipodal echo, with "virtually undiminished force", the basis of the whole scheme. That generalisation rests on the one evening of 3 July (plus Lowenstein's observations, of which no account has been found) and the short-range lamp tests [read; Physicist, Contrarian, arbiter QE revision B].

Tesla's own statements that he had done it. Several times Tesla said the global test had been performed, each in a promotional text or an interview, none with a laboratory record, witness account or signal data in the folder [read: arbiter QE revision B, from the Valone, Tesla Said and Prodigal Genius deep reads]: - December 1904, interview with Frank G. Carpenter (as quoted by the Corums): "With my transmitter I actually sent electrical vibrations around the world and received them again." - 1907: the magnifying transmitter "passed a current of one hundred amperes around the globe" (Tesla Said p.111; no voltage, frequency or method given). 100 A is a current in the antenna, not a power delivered anywhere. - The World System prospectus: "passed a current, sufficient to light more than 200 incandescent lamps, around the Globe", with "a loss not exceeding a few per cent". - 1915: voice sent "clear across the globe" from Colorado in 1899. - 1927: tests "with a generator of 1500 KW capacity" (the Corums elsewhere give 250 kW) showed the current "returning from the antipodes to its origin with undiminished strength".

Tesla had a financial stake when he made most of these statements (raising money in 1899-1904, and in 1927). Against them stand his own words: in June 1900 "while I have not as yet actually effected a transmission of a considerable amount of energy, such as would be of industrial importance, to a great distance by this new method, I have operated several model plants" [read: Century 1900, quoted by O'Neill p.172]; and in the 1916 interview, asked how far the Colorado receivers were, "Oh, 10 miles or so", adding that "these distances were small" because they were meant "to give me quantitative data" [read: research/files/tesla-1916-on-his-work-with-AC_djvu.txt, p.173, lines 9338-9362]. In the same interview he puts his greatest signalling distance at about 30 miles (New York to West Point, before 1897); asked where the grounded lamp coil of late 1899 stood, he answered "That was out in the field. I cannot tell you"; and asked for the greatest distance from Wardenclyffe, said the plant "was not yet quite ready" [read: same file, lines 2230-2243, 5677-5685, 9380-9392]. This was an interview with his own counsel for patent litigation, so Tesla had every reason to claim more, not less. The 3-4 July entry does not describe a round-the-world test, and the Notes' editor reports no great-distance measurement in the diary.

O'Neill's 26 miles and 200 lamps. Tesla's first biographer writes: "By piecing together the fragmentary material published in a number of publications ... it appears evident that Tesla ... tested his power transmission system at a distance of twenty-six miles from his laboratory and was able to light two hundred incandescent lamps, of the Edison type, with electrical energy extracted from the earth", at "an efficiency of higher than 95 per cent" [read: Prodigal Genius, printed p.171]. O'Neill names none of the publications. The deep read traces the pieces: the "200 incandescent lamps" and "a few per cent" loss are in the World System prospectus (as a current "around the Globe", not a 26-mile test), and 96-97 per cent is from Tesla's 1917 Edison Medal speech; the documented Colorado lamp tests are one to five lamps, lit by induction at about 60-100 ft or through the ground at a distance the Notes do not give; and O'Neill's own next page quotes the June 1900 caveat above [read: Prodigal Genius deep read §15b]. Valone repeats the figure citing O'Neill, so it is not a second source. The diary's silence is a gap to be explained (the diary is incomplete; the test was recorded elsewhere; no such test was made), not a refutation in itself. A size check [calc, arbiter]: 200 lamps is about 10 kW; even if a 224 kW plant radiated all its power into a hemisphere with no loss, the power density 42 km away is 2 x 10^-5 W/m^2, and a resonant receiving antenna, whose effective area is about 0.12 lambda^2, collects about 10 W at 150 kHz or 100 W at 45 kHz: 100 to 1000 times short of 10 kW. So "10 kW lit at 42 km" cannot have been done by radiation; whether some smaller test lies behind O'Neill's account is unknown.

The Notes' editor on Tesla's errors. A. Marinčić, who edited the 1978 edition for the Tesla Museum, states plainly where he thinks Tesla went wrong: what Tesla expected near 10 kHz actually occurs at much lower frequencies, the waves live in the "capacitor" between earth and ionosphere rather than in the earth itself, and the very high voltages were not needed [read: research/2026-10-08-archive-org.md §1]. This is evidence against Tesla's mechanism from the Museum's own editor (who, as below, also quotes J. R. Wait's favourable remark), and it agrees with the worked example in section 5.

Side by side.

The last row deserves a fair hearing. Tesla's picture is a resonator, not a broadcast: for a lossless resonant cavity it is correct that, in steady state, the source supplies only what the loads absorb. The question is whether the cavity's own walls (the ground and the ionosphere) absorb less than the receivers. That is a question about the guide's loss, and the measured losses answer it (section 5).

Tesla himself wrote in 1912 that the loss "is proportional to the cube of the frequency", that "with waves 300 meters in length economic transmission of energy is out of the question" and that at 12,000 m it "becomes quite insignificant" [read: Tesla Said p.132]. The direction is right: lower frequencies lose less. The size is not: at 12 km wavelength (25 kHz) the measured loss is still decibels per megametre.

Other parts of claim 1. Power through the upper air at "15 to 20 million volts" with terminals at 30,000-35,000 ft (US 645,576): the patent gives no energy budget (5,000 hp at 20 MV is 0.19 A; nothing on the volume of ionised air or what keeps it ionised) [calc, Mathematician]; no test is on record. Tesla's "18 million horsepower" and "ten million horse-power" figures: in his own 1916 words they were condenser energy "discharged in an inconceivably small interval of time", and "if you have a continuous or undamped wave, 1 kilowatt gives you only wave energy at the rate of 1 kilowatt and nothing more" [read: research/2026-10-08-archive-org.md §3]. These are peak rates, not delivered power. His own 1916 figures for the Colorado antenna (about 1,000 A, 3.5-4 million volts, a capacity of 550-660 pF) fit together: the antenna then stores 1/2 C V^2 = 4.4-5.3 kJ, which at 18 million hp (1.34 x 10^10 W) lasts 0.33-0.39 microseconds, and 1,000 A into that capacity at 4 MV implies a frequency f = I/(2 pi C V) of 60-72 kHz, inside his Colorado range [calc, arbiter revision F5; not in example.py] [read: research/files/tesla-1916-on-his-work-with-AC_djvu.txt lines 6238-6256].

4.2 Waves, the ether and "electric sound waves" (claim 2)

Starting point: Tesla saw that near a high-frequency, high-voltage terminal the electrostatic field dominates and air absorbs energy (heating, streamers, glow). His 1892 "Dissipation" letter proposes that this loss goes as (surface charge density)^2 times frequency and is carried by "sound waves of electrified air"; he says "accurate quantitative determinations ... are as yet wanting" [read: deep Dissipation letter]. The corona-loss part is mainstream. Departure: he took this to mean that Maxwell's transverse waves were the wrong picture and could not carry energy to practical distance (US 649,621) [read]; Hertz's experiments and all radio contradict that. His 1891 lecture states correctly that "electrostatic effects diminish nearly with the cube of the distance ... electromagnetic inductive effects ... simply with the distance" [read: 1891 lecture], which, read as physics, says the radiative part wins at a distance [Mathematician]. Tesla never used the word "longitudinal" in the pages read; later authors (Vassilatos, Valone, Bass, Grotz) supplied it. In the one worked version (Bass, in Valone) E is parallel to B and the Poynting vector is zero, so the wave carries no energy; Valone's chapter on Nichelson also reads "19 MeV per second" as an energy [read: deep Valone; calc, Mathematician].

4.3 Resonant circuits and the bifilar coil (claim 3)

Starting point: Tesla's wireless lamps, single-wire power (with the return path through capacitance to the surroundings) and resonant voltage rise are real and standard. His Coil patent (US 512,340, 1894) winds two strands side by side and joins them in series, so that adjacent turns differ by half the coil voltage instead of 1/N of it; with 100 V on 1,000 turns that is 50 V instead of 0.1 V between neighbours, and the stored inter-turn energy rises by (50/0.1)^2 = 250,000 [read: deep Coil patent; calc]. The patent claims only a coil whose own capacitance offsets its self-induction; it claims no gain [read]. Departure (by a later advocate): Nichelson's 1990 measurement (two 43-turn coils, 4-inch in the voltage-gain paper and Thermodynamics2, 3-inch in a Fuelless footnote: unresolved, possibly a misprint or two measurements) reports network-analyser transmission peaks of 0.18 (single coil, 19 MHz) and 0.97 (bifilar, 11 MHz), and a "voltage gain" X_L / R with R silently set to 1 ohm (2 pi f L = 24,822 and 14,173: reactances in ohms) [read: deep voltage-gain; calc]. Both measured numbers are below 1, as any passive part must be, and the "929%" (correctly 946%, 5.39/0.57) divides a transmission ratio by a reactance ratio, which are different quantities [calc]. Two genuine puzzles stay in the record: a simple series inductor of 205 uH at 11 MHz would give |S21| about 0.007, so the 0.97 peak means the set-up was not acting as a simple series inductor; and Tesla's inter-turn model predicts a 21-fold drop in self-resonant frequency for 43 turns where 1.73 was measured [calc, Contrarian, Mathematician, arbiter]. The arbiter adds a hypothesis to test, not a finding: 43 turns of 4-inch coil hold about 13.7 m of wire, whose half-wave resonance at the speed of light is about 10.9 MHz, close to the 11 MHz peak.

4.4 Energy from the medium (claim 4)

Starting point: Tesla's 1900 Century article imagines a cold "sink" into which ambient heat flows, and says himself that "we do not know of any such absolutely perfect process of heat-conversion", so that the scheme would need "continuous pumping out". So far that is consistent with the second law. But the paragraph goes on: "But evidently there will be less to pump out than flows in, or, in other words, less energy will be needed to maintain the initial condition than is developed by the fall, and this is to say that some energy will be gained from the medium. What is not converted in flowing down can just be raised up with its own energy, and what is converted is clear gain. Thus the virtue of the principle I have discovered resides wholly in the conversion of the energy on the downward flow" [read: _text/tesla-the-problem-of-increasing-human-energy-c47de7.txt, reprint p.21].

How Tesla got there: one dropped word. Tesla states the second law, after Carnot and Kelvin, as "impossible for an inanimate mechanism or self-acting machine to cool a portion of the medium below the temperature of the surrounding, and operate by the heat abstracted" [read: reprint p.19]. Kelvin's 1851 wording ends "below the temperature of the coldest of the surrounding objects" [web: https://collection.sciencemuseumgroup.org.uk/people/cp37484/william-baron-kelvin-thomson]. The word matters. Tesla's first example, a thermopile of metal bars from the earth to outer space that would run a motor "until the media below would be cooled down to the temperature of the outer space" [read: pp.19-20], uses outer space as its cold side, and outer space is the coldest surrounding object. That is an ordinary heat engine between two reservoirs, allowed by Kelvin's law (the arbiter, revision F: consistent with the second law). Tesla reads it as an exception only because his paraphrase leaves "coldest" out. The sink is different: there, the cold is made inside the machine and must be kept up from the same surroundings.

Departure (Tesla's own). This is a claim of a partial net gain from a single ambient reservoir, and the calculation of section 3.5 rules it out. Per joule of heat Q_h taken from surroundings at T_h = 300 K, an ideal engine with its sink at T_c = 77 K gives work 0.743 J and passes Q_c = 0.257 J down to the sink. "Raising up" that 0.257 J to ambient again is refrigeration, and the least work it can cost is Q_c (T_h/T_c - 1) = 0.257 x 2.896 = 0.743 J. Gain minus cost is zero, for any pair of temperatures: Q_c (T_h/T_c - 1) = Q_h (1 - T_c/T_h) because Q_c/Q_h = T_c/T_h for the ideal engine [calc, Mathematician; arbiter QE revision A]. Tesla's error is to treat heat like water, which can be lifted back "with its own energy" after its fall; heat that has dropped to T_c has lost the ability to do the work of lifting itself. Arbiter's verdict: Refuted by calculation for the partial-gain step (changed from "not refuted"). His caveats stay beside it: he knew no perfect process, he "cannot hope to produce a self-acting machine deriving energy from the ambient medium for a long time yet", and he reports that in the liquid-air case the consumer's gain is "offset by an equal loss of the producer" [read: same, reprint pp.21-22]. It is a hypothesis stated in good faith from a heat-as-fluid picture, not a hoax.

Departure (later readers). Nichelson's reading, that Tesla meant net work from one ambient reservoir, is therefore closer to the 1900 text than an earlier version of this primer said; his further step, that a closed unipolar dynamo or bifilar coil does this, is his own and is Refuted by calculation on its own grounds. Vassilatos and Lindemann link the paragraph to Edwin Gray's, Moray's and Baumann's "radiant energy" devices; Lindemann's 1995 "Self-Acting Engine" article names working models (Doczekal in the 1930s, Schaeffer and Serogodski DE 42 44 016, Wiseman) with no power-in or power-out figures. His proposed cycle (a compressor, a heat exchanger warmed by the air, a throttle that flashes part of the liquid, a turbine, and no condenser), whose turbine is said to give more work than the compressor takes, exchanges heat with one reservoir only, so the Kelvin form of the second law rules out net work: Refuted by calculation (arbiter revision F2). His 1994 article holds that an "Etheric Energy Field" breaks the second law (Not testable as stated) and that the equivalence of mechanical work and heat "is not known" (Tested, not supported: it has been measured repeatedly since Joule [memory: high]); its figures (a "100,000 to 1" weather-engineering gain that "has never been done", "twice as much hydrogen" attributed to Tewari) come with no instrument or control [read: Free Energy Secrets deep read, Retry 137-146 and 147-156]. No output measurement of any such device is in the folder [read: deep Fuelless, Free Energy Secrets deep read §4b]. In the same 1900 article Tesla also reports chemical-energy devices: a limestone engine that "operated satisfactorily" and a cold coal battery whose "lack of success has been complete" (no figures) [read: reprint p.17]; neither draws on ambient heat, and he reports no measured output of a self-acting engine anywhere in pp.15-24.

Gray, as the record stands. Gray's 1973 demonstrations (reported in the National Tattler, 1 July 1973, and echoed elsewhere) were verbal and unmetered; the witnesses named are company officers (Hackenberger, Lens) and one outside guest, C. V. Wood Jr. of McCulloch Oil, quoted as amazed. A scale check shows why the reports cannot decide the question [calc, arbiter, assumptions flagged]: throwing a 1.25 lb magnet 2 ft takes about 3.4 J, which a 0.75 uF capacitor at 3,000 V holds; and a 150 W load run for 10 minutes from an assumed 12 V, 15 Ah battery uses 90 kJ, 14 per cent of its charge, a change a voltmeter would not clearly show. Lindemann, an advocate, built the 1975 patent (US 3,890,548) and reports it "doesn't perform anything like what was described", recovering "only a negligible amount of energy" (no bench data); he places the real effect in Gray's 1986 and 1987 patents [read: Free Energy Secrets deep read §2]. The book also gives Gray's legal history: a raid by the Los Angeles District Attorney on 22 July 1974, a grand-theft charge later dropped, and a March 1976 guilty plea to two minor SEC (Securities and Exchange Commission) violations; "unprovoked" and "bogus" are Lindemann's words, and no court or SEC document is in the folder. Arbiter's verdict on the demonstrations: Never properly tested; Lindemann's failed build is one unquantified negative result by an advocate, weighing against the patent's described performance without being a controlled test.

What the air really offers. Tesla's own patent US 685,957 (1901) collects charge from the air with an insulated plate and a condenser; he reports charging a condenser "even to the point of rupturing the dielectric" [read]. Size of the real gradient: the fair-weather field is about 120 V/m and the air-earth current about 2 pA/m^2 [web: https://en.wikipedia.org/wiki/Global_atmospheric_electrical_circuit]; a 1 km^2 collector 100 m up gets about 2 microamps at 13 kV, about 0.03 W [calc, Mathematician]. Tesla's 1902 and 1931-33 statements that he had harnessed "cosmic energy" are interview quotations with no device or witness in the folder; he was raising money in 1904 and financially dependent in 1931-33 [memory: medium], which is his stake, stated beside what he said.

4.5 The disc turbine (claim 5)

Starting point: viscous drag on closely spaced discs is real, and the machine runs, reverses and tolerates dirty fluids. Tesla's associates' tests are real measurements: Lowenstein's 1911 tables give 102.8 brake hp at 53.4 lb of steam per bhp-hour and 77 hp at 35 lb, with a Prony brake, condensate weighed and the record kept by Prof. C. D. Richards [read: deep Hayes]. (The name differs in the sources: Lowenstein writes "C.D. Richards", while Hayes elsewhere prints "C.B. Richards, Professor Emeritus of Mechanics, Yale" [read: Hayes; QE spot check 4]; unresolved.) Departure: Tesla stated "80 to 90 per cent". Recomputed against ideal expansion (steam properties from IAPWS-IF97, section 2), his own 38 lb/hp-h run at 125 psia is 43 per cent; by his own "130 Btu" heat drop 52 per cent; Lowenstein's 35 lb run (176 psia to 21 inches of vacuum) is 29 per cent; and Lowenstein's first test (102.8 bhp at 53.4 lb/bhp-h, 100 lb gauge = 114.7 psia, to a 15 inch vacuum = 7.33 psia) is about 25 per cent: saturated steam expanded ideally between those pressures drops 193 Btu/lb, so the ideal rate is 2545/193 = 13.2 lb/hp-h, and 13.2/53.4 = 24.6 per cent (23.0 per cent if the steam had 100 F of superheat, which the test does not state) [calc, arbiter QE revision E]. The band is therefore about 25-52 per cent, the low end resting on an assumed steam condition. Brake horsepower in that test includes the gear losses ("No allowance was made in these tests for loss of power in gear" [read: Hayes]), so the turbine alone did somewhat better. The Allis-Chalmers engineer Hans Dahlstrand reported 38 per cent "mechanical efficiency" (definition not stated), disc distortion and a need for gearing, known only through O'Neill's quotation [read: Prodigal Genius]. "10 hp per pound" has three different mass bases in the sources (about 3 hp/lb for the 1906 model, a slogan of 10-20, 0.5 hp/lb for the whole 400 lb Waterside machine) [read: deep Hayes, Mathematician]. Open engineering point kept in the record: Guha's group blames much of the gap on the nozzle, so rotor-only efficiency is not settled by the data cited.

4.6 Teleforce and the papers (claim 6), and priority (claim 7)

Teleforce: Tesla (1934, 1940) described a beam of tiny particles to melt aircraft engines at 250 miles. No apparatus, test data or full specification is on record, but written outlines did exist: John Trump's abstracts of 30 January 1943 list 17 exhibits (A-Q) [read: FBI 02 deep read, addendum; arbiter QE revision C]: - Exhibit F: an electrostatic generator and an "open-ended vacuum tube" accelerating "presumably electrons" into a "concentrated non-dispersive" beam through air. Trump: "incapable of the transmission of large amounts of power in non-dispersed beams over long distances", and the disclosures "would not enable the construction of workable combinations of generator and tube even of limited power". - Exhibit H: letters to British representatives (28 Aug 1936, 26 Oct 1937, 15 Dec 1937, 5 Apr 1938) offering a "death ray" for a fee; the reply of 7 Jan 1938 was "a polite expression of disinterest". Valone quotes a War Office reference "84/T/3458" and a 1937 price of £10 million [read: digest Tom-Valone.06 p.126]. - Exhibit J, in Tesla's hand ("Method of Producing Powerful Radiations"): the only method given is a jet of fluid making a vacuous space round a terminal. - Exhibit Q: a signed agreement of 20 April 1935 with Amtorg, the Soviet trading body, $25,000 received, for plans for 50 million volts, "very small particles in a tube open to air", range "a hundred miles or more", speed "not less than 350 miles per second". The file holds no Soviet reply.

Trump was an OSRD (Office of Scientific Research and Development) evaluator with an institutional stake; his judgement is his, and the full Tesla texts are in the Tesla Museum or the Alien Property file and have not been read here. A check on Tesla's numbers [calc, arbiter]: 350 mi/s is 563 km/s, 0.19 per cent of the speed of light; electrons at 50 MV would move at essentially light speed, so the Amtorg particles must be heavy ones. Any known particle beam through 400 km of low-altitude air meets about 170 nuclear interaction lengths [calc, Mathematician], so the known-particle form fails whatever the particle.

Papers: sealed by the Alien Property Custodian on 9 January 1943 (not seized by the FBI, which nonetheless did inquire); examined by Trump, who found them "speculative, philosophical, and somewhat promotional" (the only scientist's report, full text not online [web: https://www.pbs.org/tesla/ll/ll_mispapers.html]). Later military interest is documented in the FBI file [read: FBI 01 and 02 deep reads, arbiter QE revision D]: - January 1943: Bloyce Fitzgerald told the FBI that Tesla said his wireless-power experiments "had been completed and perfected", that a working model "which cost more than ten thousand [dollars]" was in a Governor Clinton Hotel deposit box, and that there were "some eighty trunks" of plans. The FBI confirmed the hotel had held Tesla property since 1932 as security for a $400 debt, and did not examine it; Trump's party later called the hotel items "standard electrical measuring instruments in common use several decades ago". Fitzgerald's stake is unclear; Trump's is stated above. - 21 August to 11 September 1945 (from Cheney's quotation of Office of Alien Property (OAP) letters; the originals are not in the file): Air Technical Service Command asks for a trip for Pvt Fitzgerald; Col. Holliday of the Equipment Laboratory at Wright Field asks for photostats of the Trump-annotated exhibits; OAP sends them to Lt Robert E. Houle, "please return"; Cheney says they were "never returned". A 1945 FBI informant letter separately places Fitzgerald at Wright Field. - 17-26 October 1945: some 75 boxes and trunks still at Manhattan Storage; a former Tesla protege and two Wright Field men ask the FBI for access and are referred to the Custodian; the file does not say whether they saw the effects. - 6 December 1960: a caller "making a research study for U.S. Air Force on subject of geophysics" asks for the papers. - 9 February 1981: Lt Col Allan J. MacLaren, Office of the Under Secretary of Defense (Research and Engineering): "certain of Tesla's papers may contain basic principles which would be of considerable value to certain ongoing research within the DoD" (Department of Defense). The FBI's replies of March 1981 say it never held the papers, and disagree with each other on whether they were released to Sava Kosanovic in February 1943 or still sealed in October 1945; the "1952 release" given in an earlier version of this primer is not established. - 1983: an FBI airtel records Wright-Patterson staff seeking the papers because the Soviets "allegedly" used them.

These records support the reading that the papers were copied for military interest; nothing in the folder shows what Wright Field did with the photostats. The name "Project Nick" itself has no primary record.

Priority. The rotating magnetic field, induction motor, polyphase system and the Tesla coil are documented and established. Radio: Tesla's tuned, grounded-terminal patents predate Marconi's; the 1943 Supreme Court case (Marconi Wireless Telegraph Co. v. United States, 320 U.S. 1) invalidated a Marconi claim but did not decide who invented radio, and the sources the arbiter could open say Lodge and Stone were decisive [web, arbiter]. X-rays: Tesla's known shadowgraphs date to 1896, after Röntgen's announcement of 8 November 1895; earlier Crookes-tube work was cut short by the laboratory fire of 13 March 1895 [web, arbiter]. Cosmic rays, artificial radioactivity, the atom smasher and the electron microscope: O'Neill concedes the records "are not available" [read]. Further priority items in the record: the 1898 "telautomaton" (US 613,809), a radio-controlled boat, which supports a priority claim for radio control; the 1907 Tesla-Poulsen priority letters; and John Stone Stone's testimony that Tesla was the first to see the role of the upper atmosphere [read: facts.json; digest Tesla-Said.07 pp.104-105, .11 pp.182-183].

4.7 Signals from another planet (claim 8)

Tesla's own words: in Collier's Weekly (9 February 1901, "Talking with Planets") he wrote that changes in his Colorado receiver came "periodically, and with such a clear suggestion of number and order that they were not traceable to any cause then known to me"; he "could not decipher their meaning", and "the feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another". In 1919 they "might have come from Mars" (New York Herald, 12 October); in 1921 "a regular repetition of numbers" that "must have emanated from Mars"; in 1937-38 he described a device to flash energy "through interstellar space to any distance without the slightest dispersion" [read: Tesla Said deep read §A]. Note that the 1901 text speaks of number and order but not of numbers repeated; the "numbers" appear twenty years later. In 1921 Tesla attributed other people's 1919-21 "planetary signals" to undertones of transmitters. No laboratory record of such signals has been found in the Notes pages read; the passage on "intelligent beings on a neighbouring planet" is the copy of a statement Tesla sent to the North American (Philadelphia) on 8 December 1899, at a journalist's request, not a laboratory record [read: Notes lines 17127-17149]. Ordinary candidates for periodic natural radio signals at his receiver's 8-22 kHz include lightning, magnetospheric "whistlers" (lightning signals dispersed along the earth's magnetic field) and local interference; none is excluded or confirmed by the record. The Corums, who have a stake in Tesla-based technology, read the signals as radio emission from Jupiter (Corum 2003; untested). Arbiter's verdict: Never properly tested.

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5. Worked example: can the earth carry Tesla's standing waves and his power "almost without loss"?

This takes Tesla's own numbers, puts in the measured losses of the earth-ionosphere guide, and asks two questions: would an antipodal echo be strong enough to make the nodes he described, and how much power would reach a distant receiver? Every number is reproduced by example.py (run: .venv/bin/python review/Tesla/example.py).

Step 1. What frequency do his observations imply? Nodes are half a wavelength apart. If the storm moves at speed v and the receiver peaks every T = 0.5 h, the node spacing is v T and the wavelength lambda = 2 v T. For v = 20, 40, 60 km/h: node spacing 10, 20, 30 km; lambda = 20, 40, 60 km; at light speed, f = c / lambda = 15, 7.5, 5 kHz. Tesla's own 1905 wavelengths of 25-70 km give 12 to 4.3 kHz. [calc] Both readings agree, they lie inside his "smaller than twenty thousand per second", and they agree with the Corums' statement that his receivers worked "primarily in the 8 kHz to 22 kHz range" [read: research/files/corum-2003-tesla-planetary-radio-signals.pdf, via the Mathematician]. So the waves in question are VLF, about a thousand times the frequency of the Schumann modes.

Step 2. His timing figure checks out as arithmetic. 0.08484 s x 471,240 km/s = 39,980 km, one circumference (40,030 km). 471,240 / 300,000 = 1.5708 = pi/2, and 2 x 12,726 km / 300,000 km/s = 0.08484 s: light speed across the earth's diameter and back, projected onto the surface [calc; first noted in the Valone deep read]. This is self-consistent; the patent does not say how it was measured.

Step 3. How strong is the "returning" wave? Take a receiver at distance d from the source on a sphere. It gets the wave the short way round (path d) and the wave the long way round (path C - d, C = 40,030 km). On a sphere both arrive with the same spreading factor, because |sin(d/a)| = |sin((C - d)/a)|; so their amplitude ratio r depends only on attenuation over the extra path C - 2d. This is the most favourable version of Tesla's antipodal echo: no reflection loss at all. With d = 300 km (his 1904 figure) the extra path is 39.4 Mm.

[calc] For a pattern with max/min = 2, r must be 1/3, which needs less than 0.24 dB/Mm. The ELF line comes from the Schumann Q: a mode loses amplitude as exp(-pi f t / Q); at speed about c that is pi f / (Q c) nepers per metre, which for f = 7.8 Hz and Q = 3.3 is 0.22 dB/Mm (1 neper = 8.686 dB) [calc]. (Using the group velocity of about 0.8 c instead raises the figure by a quarter; the conclusion does not change.)

What this says. At 8 Hz the earth-ionosphere cavity does carry a global standing wave: that is the Schumann resonance, and Tesla's "six per second" in 1900 was a fair anticipation of it. At the 4-15 kHz his own data imply, the long-way wave arrives 40 to 120 dB weaker than the direct one, and the node pattern from it is a ripple of 2 per cent at best. Lightning signals vary far more than that from flash to flash. The antipodal echo "with virtually undiminished force" cannot be what Tesla's relay saw.

A published counter-claim: cavity Q "as high as 1000". The ELF row rests on Q = 3.3, and the figure is disputed in the folder. Van Voorhies (in Valone, p.140) writes that Q is "generally reported" at about 6-8, but that Sutton and Spaniol (1988, magnetic measurements at 3-30 Hz) "found that the previously measured Q values were limited by instrument noise" and "measured levels as high as 1000", confirmed by others through personal correspondence; Corum, Corum and Spaniol ("Concerning Cavity Q", 1988) argue that low Q "does not necessarily limit" wireless power; and Grotz gives an estimated cavity loss of "about 6 percent per round trip" [read: Valone deep read; digests Tom-Valone.07 p.140, .08 p.162]. No instrument, site or definition of Q is given, and the papers themselves have not been seen. Against them, in the same book, the Corums' own table gives accepted Q of 3.8-7.8 and 3.2-6.4 from Tesla's data, and the observed Schumann peaks have a spectral width of about 20 per cent [web: https://en.wikipedia.org/wiki/Schumann_resonances], which means Q = f / (width) of about 5. What each value would give, in the same two-path geometry (example.py, Step 3b) [calc]:

So if Q = 1000 were a property of the cavity as a store of power, the ELF row would be close to lossless, and at 0.0007 dB/Mm it would even meet the 0.0011 dB/Mm that Tesla's "small fraction of one per cent" needs (Step 4). This is stated here because it matters, and the reader should weigh it. Three things it does not change (arbiter QE revision B): (1) the VLF rows, and so Tesla's own 4-15 kHz waves and his "smaller than twenty thousand per second", rest on measured VLF attenuation, not on Q; (2) a narrow spectral line seen in natural noise says little about how much power a man-made transmitter can put into the cavity: the ELF transmitter tested under Project Sanguine radiated about 1 W from about 2.6 MW of input [web, via Mathematician], a coupling loss of order 10^-7 that a high cavity Q does not remove; (3) Tesla's scheme was not an 8 Hz scheme. The arbiter's verdict: high-Q ELF cavity storage as a power path is Never properly tested; the figure of 1000 is one reported measurement, kept in the record with the 4-8 figures beside it.

A related measurement in the folder: Rauscher and Van Bise (Valone ch.14; they hold a patent on the detector they used) recorded ELF magnetic spectra at Portland and in the Bay Area in 1979-87 and claim a 3.16 Hz earthquake precursor with "approximately 84% accuracy"; the chapter gives no statistics for that figure and no calibration method [read: Valone deep read; arbiter QE revision H]. It bears on signals in the cavity, not on power transfer.

That does not make the 3 July observation false. It means the cause must be something nearer: Tesla's own first guess in the diary (a local reflection), interference between waveguide modes or between ground and sky paths, several storm cells at different distances, the evening change in the ionosphere at sunset, or his repeated re-setting of the relay threshold. The reviewers disagree on which is best, and none can be decided from the diary, which has no trace record, no distance log and no receiver frequency (arbiter, Open question 1).

Step 4. How much power reaches a distant receiver? Launch P0 = 1 MW into the guide (a perfect launch; see Step 5). At d = 10,000 km the band of height h = 70 km has cross-section 2 pi a sin(d/a) h = 2.80 x 10^12 m^2, so the intensity with no loss is 1 MW / 2.80 x 10^12 m^2 = 3.57 x 10^-7 W/m^2. A collector of 1 km^2 (far bigger than any real antenna) catches 0.36 W. With 2 dB/Mm over 10 Mm (20 dB, a factor 100) it catches 3.6 mW: 3.6 x 10^-9 of the power sent. At the antipode, after 20 Mm, 10^-4 to 10^-6 of the power survives the guide losses alone (40-60 dB) [calc; these are the arbiter's corrected figures].

Now ask what Tesla's claim needs. A loss of at most 0.5 per cent ("a small fraction of one per cent") over 20 Mm is 10 log10(1/0.995) = 0.022 dB, or 0.0011 dB/Mm. That is about 1,800 times below the measured daytime VLF loss and about 200 times below even the ELF loss derived in Step 3 [calc]. In the resonator picture (power taken "only where it is collected"), the same numbers mean the walls of the cavity absorb the energy long before receivers on the far side can take it.

Step 5. The launch. For a short, top-loaded vertical antenna of height H, the radiation resistance is R_rad = 160 pi^2 (H / lambda)^2 [memory: high]. With H = 57 m (Wardenclyffe scale, the Physicist's figure) R_rad = 1.28 ohm at 150 kHz and 0.008 ohm at 12 kHz. With a ground-system loss resistance of a few ohms (2 ohm assumed here [memory: medium]) the fraction of input power radiated is 39 per cent at 150 kHz and 0.4 per cent at 12 kHz [calc]. Tesla designed for radiation "reduced to an insignificant quantity" [read: 1904]; in the standard picture the radiated part is exactly what travels to distant receivers, so reducing it reduces what can arrive.

Step 6. "Activity" is not power. 18 million hp = 13.4 GW. A 0.0225 uF condenser (the 3 July 1899 diary value) charged to 50 kV (assumed) holds 28 J, enough to sustain 13.4 GW for 2.1 nanoseconds [calc]. Tesla's own 1916 figures for the antenna (550-660 pF at 4 MV) give a bigger store, 4.4-5.3 kJ, which lasts 0.33-0.39 microseconds at that rate (section 4.1) [calc, arbiter revision F5]; either way it is a burst, not a power. The 1904 "ten million horse-power, one per cent of which is amply sufficient to 'girdle the globe'" [read: 1904 article p.3] is 7.5 GW of peak activity, 75 MW for the one per cent [calc]. Tesla's own 1916 definition makes these peak rates of a condenser discharge [read], so they say nothing about net power.

What the example shows. Tesla's geometry is self-consistent, his lowest-frequency estimate was a real anticipation, and his VLF receiver almost certainly did detect distant lightning. What breaks is the one assumption he wrote into US 787,412: an earth of "inappreciable resistance" transmitting "without sensible ... attenuation". Put in the measured attenuation and both the global standing wave at kHz and the low-loss power delivery disappear. The one place the conclusion could move is at 8 Hz, if the disputed cavity Q of up to 1000 were confirmed as a property of the cavity as a power store; that is open, and it would still leave the problem of putting power into the cavity.

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6. Evidence table

Verdicts are the arbiter's, on the Step 2 scale.

Where the record goes dark (anomalies, not neutral gaps). (1) Wardenclyffe: dense records to 1904 (Tesla to Rankine, 19 April 1904: the plant "could now be finished in three to four months", $100,000 needed; Tesla wrote that an enclosed statement by the patent lawyers Kerr, Page and Cooper showed his patents to be "controlling", and valued them himself at "not less than $5,000,000"; the lawyers' text is not in the scan [read: research/files/tesla-papers-1904-rankine-letters_djvu.txt lines 307-311]; Tesla was raising money and so an interested party), then foreclosure (action 1915, judgment 20 April 1922) and demolition in July 1917, for which the record holds two accounts: The Sun (New York, 19 July 1917) says the Federal Government dynamited the tower "as a precaution", while its own 5 August feature says the buyer is "not known" [read: research/2026-10-08-chronicling-america.md]; Anderson (1992) says it was destroyed so the property could be developed commercially. The two are not exclusive. The foreclosure-appeal record (1922) is now read: Tesla describes a well-equipped plant, including condenser tanks and his own oscillating apparatus "used in Colorado"; a 1915 bill of sale to the hotel company (Hallock to Waldorf-Astoria), entered as a defendants' exhibit (Exhibit B; who drew up the schedule is not stated), lists only conventional engine, boiler, generator and machine-shop equipment, "including but not limited to", with no oscillator or condensers; and the creditors' engineer, Bingham, describes a building left open and rifled from about 1913, with books and papers on the floor and fittings stripped [read: research/files/tesla-1916-on-his-work-with-AC_djvu.txt, Appendix III]. Where Tesla's special apparatus went (removed earlier, scavenged, or under a generic inventory line) is open; the 1915 Tesla-to-Holmes bill of sale and the storage records of Tesla's effects would decide. Tesla testified that the plant could have received and transmitted, "but not to the extent" of the finished plant; no transmission measurement from Wardenclyffe exists in any document read. Salvage and Navy records would decide the tower's end. No record shows that a failed experiment ended the programme; equally, no completed large transmission test is on record. (2) The 1943 papers: little of value (Trump; the 1981 FBI letters), copied for military interest, or lost between sealing and release. Reading (b) now has documentary support (the 1945 Wright Field photostats, "never returned"; the 1945 Wright Field request for access; the 1981 DoD memo; section 4.6), though nothing shows what was done with the copies; the name "Project Nick" has no primary record. NARA (the US National Archives) Record Groups 131 (Alien Property) and 342 (Wright Field), the Houle correspondence, Manhattan Storage and New York Taxation Department records, and the Tesla Museum archive (163,911 call numbers) would decide. (3) Viziv/CPG: a built tower, more than 100 patents citing US 787,412, and no published field-strength measurement found; the founders (J. F. and K. L. Corum) have a stake. (4) The Colorado Springs raw charts. (5) The Allis-Chalmers report and Richards's log. (6) Any metered test of a Gray, Moray or Baumann device; and Gray's prototypes, which the book says the District Attorney never returned after the 1974 raid (readings: unremarkable devices in a securities dispute; suppression; business failure; deciding records: Los Angeles County court and DA files, the SEC file, Zetech records). (7) John B. Flowers's 1925 proposal to test Tesla's system, shown to H. L. Curtis and J. H. Dillinger of the Bureau of Standards and declined, known only from a 1999 newsletter quoted by Valone (readings: declined on engineering judgement; for lack of funds or interest; the account is partial; deciding records: Bureau of Standards (NIST) and National Archives files for 1925, and Flowers's own document) [read: Valone deep read D]. (8) Golka's full-size coil at Wendover and the 1986 proposal to excite the cavity with it: no published measurement (readings: no funding; null or unpublished results; used only for lightning simulation; deciding records: Golka's contract reports, the 1986 proposal, the 1988 symposium proceedings). (9) Tesla's 1930s dealings with Amtorg and the British Government, documented in abstracts only (deciding records: NARA, the UK National Archives under War Office reference "84/T/3458" as quoted by Valone, the Tesla Museum).

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7. What a learner should take away

What is solid. Tesla's resonant-circuit engineering is the real thing: tuned coupled circuits, the quarter-wave grounded resonator, voltage rise by Q, wireless lighting in strong high-frequency fields, coils with built-in capacitance, and the induction motor and polyphase power system. His idea that the earth plus its "conducting atmosphere" forms one resonant electrical body, with a lowest frequency near "six per second", was stated in a 1900 patent filing, decades before W. O. Schumann's 1952 prediction and the measurements of about 1960 [memory: high]; the editor of his Notes quotes J. R. Wait (1974) calling it "an intriguing similarity with later developments in ELF communications" [read: via research/2026-10-08-archive-org.md; the editor, A. Marinčić, worked for the Tesla Museum, which published the book]. His VLF receiver in Colorado was, in effect, an early sferic (lightning-signal) detector. His disc turbine runs.

What is wrong, and why it is instructive. The power claims fail on one hidden assumption: a planet of "inappreciable resistance". Once the guide's measured attenuation is included, a kHz wave dies long before it can come back from the antipode, and a receiver catches only its own slice of a spreading wave. The lesson is general: a resonance argument is only as good as the Q of the resonator, and the Q is set by the losses you left out. A second lesson is in the numbers: "18 million horsepower" was a peak rate during a burst lasting nanoseconds (the primary condenser) to about a third of a microsecond (his 1916 antenna figures), as Tesla himself said in 1916; reading peak "activity" as power is the commonest mistake in later free-energy literature about Tesla. A third is in the record, and it is not the simple story an earlier version of this primer told (that the diary was cautious and the bold version appeared only in print). On 3-4 July 1899 the diary is cautious about one thing, where the waves were reflected ("difficult to believe that they were reflected from the opposite point"); by January 1900, after lighting lamps through the ground, it already says the stationary waves prove "the feasibility of the project almost beyond any doubt". What the patent and the 1904-05 articles added was the antipodal echo "with virtually undiminished force" and, later, statements that a global test had been done. Tesla was raising money when he wrote most of these, which is his stake; it does not show that he invented the claim for investors, since the same confidence appears first in his private notes. A fourth: always check the primary text, in both directions. His advocates added things he never wrote ("longitudinal waves", a "voltage gain" from a 1-ohm assumption). But the claim of a partial net gain from the ambient medium is Tesla's own ("what is converted is clear gain", 1900), and it was this review, not the advocates, that first stopped the quotation too early. A fifth: the editor of his Notes, Marinčić, himself lists Tesla's errors (the wrong frequency range for the earth's resonance, the waves in the earth rather than in the earth-ionosphere gap, unnecessary high voltage), which agrees with the worked example.

What is genuinely open. (1) What made Tesla's receiver turn on and off every half hour on 3 July 1899: a modern repeat with a recording receiver and lightning-location data, or a search of sferic-network archives for half-hour modulation, could answer it. (2) Why the 1990 bifilar coil measurement shows a 0.97 transmission peak and a self-resonance shift far smaller than Tesla's inter-turn model predicts (test: half-wave resonance of about 13.7 m of wire). (3) The rotor-only efficiency of a disc turbine once nozzle losses are separated. (4) The true Q of the earth-ionosphere cavity as a store of power at 8 Hz: Q about 5 from the width of the Schumann peaks, or up to 1000 as Sutton and Spaniol are reported to have measured, and how much power a transmitter can actually inject (section 5, Step 3). (5) What lies behind O'Neill's 26-mile, 200-lamp account. The Notes entries read so far (to 2 January 1900) record no distant test, the 6 August water-pipe test has no data, and Tesla in 1916 gave no Colorado distance beyond about 10 miles; the 3-7 January 1900 diary text is still unread. (6) What the 1943 papers and the teleforce exhibits contained in full, what Wright Field did with the 1945 photostats, what Lowenstein saw, what the Allis-Chalmers report said, why Golka's coil and the Viziv/CPG tower have published no transmission data, and what the Bureau of Standards made of Flowers's 1925 proposal.

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8. Check yourself

1. A series RLC circuit has L = 10 uH, C = 0.04 uF and R = 0.5 ohm. What are its resonant frequency and Q, and what is the capacitor voltage if it is driven at resonance by 1 kV? Is the circuit producing power?
2. Tesla's receiver peaked every half hour while a storm moved away at 30 km/h. If this were a standing wave travelling at light speed, what frequency would it be? Is that closer to the Schumann resonance or to VLF?
3. Using 2 dB/Mm, what fraction of the power launched into the earth-ionosphere guide survives a 20 Mm trip to the antipode, before spreading? How does that compare with "a loss not exceeding a small fraction of one per cent"?
4. Why does a measured network-analyser transmission of 0.97 not show a "voltage gain", and why can it not be compared with X_L / R?
5. Tesla said in 1916 that 1 kW of generator could give "2,000, 3,000, 4,000, or 5,000 kilowatts" of "activity" with damped waves. How can that be true without violating energy conservation?

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9. Further reading

Mainstream. - D. J. Griffiths, Introduction to Electrodynamics: chapters 7-9 and 11 (induction, Poynting's theorem, waves, radiation) [memory: high]. - J. D. Kraus, Antennas (radiation resistance of short and top-loaded monopoles); D. M. Pozar, Microwave Engineering (S-parameters, resonators). - J. R. Wait, "Historical background and introduction to the special issue on extremely low frequency (ELF) communications", IEEE Transactions on Communications COM-22 no. 4 (April 1974), cited by Marinčić [read: via research note; title from memory, medium]. - K. G. Budden, The Waveguide Mode Theory of Wave Propagation; A. P. Nickolaenko and M. Hayakawa, Resonances in the Earth-Ionosphere Cavity (Kluwer, 2002) [memory: high]. - G. P. Hoya and A. Guha, "The design of a test rig and study of the performance and efficiency of a Tesla disc turbine", Proc. IMechE Part A 223 (2009) 451-465 [read: research/files]; W. Rice, J. Eng. Power 87 (1965) 29-36 [read: via Hoya and Guha]. - Wikipedia articles on Schumann resonances, very low frequency, and the global atmospheric electrical circuit, as quick numerical references [web, URLs above]. - W. B. Carlson, Tesla: Inventor of the Electrical Age (Princeton, 2013), a historian's biography [memory: high].

Tesla's own key works. - Colorado Springs Notes 1899-1900, ed. A. Marinčić (Nolit, Beograd, 1978): the 3-4 July 1899 entry, the arrester experiments of 24 July and 26 August, and the photograph notes of 1-2 January 1900 (induction and ground-coupled lamps, the "feasibility" sentence) [read: research/files]; the editor's commentary on Tesla's errors. - "The Transmission of Electrical Energy Without Wires", Electrical World and Engineer, 5 March 1904 [read: research/files]. - US patents 645,576 and 649,621 (1900, transmission through the natural media), 787,412 (1905, "Art of Transmitting Electrical Energy Through the Natural Mediums"), 1,119,732 (1914), 512,340 (Coil for Electro-magnets, 1894), 685,957 (radiant energy, 1901), 1,061,206 (turbine, 1913) [read: Complete Patents]. - Lecture before the AIEE, 20 May 1891, and the 1892 London and 1893 lectures, in T. C. Martin, The Inventions, Researches and Writings of Nikola Tesla (1894) [read]. - "The Problem of Increasing Human Energy", Century, June 1900, especially reprint pp.19-22 (the sink argument and "clear gain") and the Colorado passages [read]. - "Talking with Planets", Collier's Weekly, 9 February 1901 [read: in Tesla Said]. - "Famous Scientific Illusions", Electrical Experimenter, February 1919 [read]. - Nikola Tesla on His Work with Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, ed. L. I. Anderson (1992), the 1916 interview, and Appendix III, the 1922 Wardenclyffe foreclosure appeal [read: research/files]. - J. T. Ratzlaff (comp.), Tesla Said (1984) [read]. - J. J. O'Neill, Prodigal Genius (1944), the first biography, by a friend; useful but a source of several unsupported priority claims [read].

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Answers

1. f = 1/(2 pi sqrt(10e-6 x 0.04e-6)) = 252 kHz. omega L = 2 pi x 252e3 x 10e-6 = 15.8 ohm, so Q = 15.8 / 0.5 = 32 and V_C = 32 kV. No power is produced: the voltage builds up from stored energy, and in steady state the source supplies exactly the power dissipated in R (here (1 kV)^2 / 0.5 ohm = 2 MW in this idealised case, all of it from the source).
2. Node spacing 30 km/h x 0.5 h = 15 km, wavelength 30 km, f = 3e8 / 3e4 = 10 kHz. That is VLF, about 1,300 times the 7.8 Hz Schumann frequency; at VLF the guide's loss (Step 3) is far too high for a global standing wave.
3. 2 dB/Mm x 20 Mm = 40 dB, so 10^-4 survives (99.99 per cent lost). Tesla's claim needs at most about 0.5 per cent lost, i.e. less than 0.0011 dB/Mm, about 1,800 times below the measured value.
4. A passive two-port cannot have |S21| above 1, so 0.97 is a transmission of 97 per cent of the wave, not an amplification. X_L / R with R assumed to be 1 ohm is just the reactance in ohms (14,173), a different quantity with different units; dividing one by the other compares unlike things.
5. "Activity" is a peak rate. The condenser is charged slowly (say over a millisecond at 1 kW) and dumps its stored energy in a few microseconds, so the instantaneous rate is thousands of times higher; the average power is still 1 kW. Tesla said exactly this: with an undamped wave "1 kilowatt gives you only ... 1 kilowatt and nothing more".

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Corrections to earlier documents

• mathematician.md, Corrections item 2, and arbiter.md, table row "6.6 Hz 'Jackson' lowest mode". Both treat Tesla's "about 6 Hz" lowest-frequency estimate as reported only second-hand (through Marinčić quoting Jackson), and the arbiter keeps "6-6.6 Hz as Tesla's reported estimate (Marincic, an interested party as publisher)". Tesla's own patent states it: "The lowest frequency would appear to be six per second, in which case there will be but one node, at or near the ground-plate, and, paradoxical as it may seem, the effect will increase with the distance and will be greatest in a region diametrically opposite the transmitter" [read: Complete Patents, US 787,412, PDF p.425]. Correction: "six per second" is Tesla's own figure, in a patent filed 16 May 1900; only the "6.6 Hz for a perfectly conducting sphere" attributed to Jackson remains unverified.
• claims.md, claim 1, "The only quantitative circuit in the patents is a 0.04 uF, 50 kV, 230-250 kHz 'model plant'". True of circuit values, but US 787,412 also gives quantitative propagation conditions not recorded in claims.md or the reviews: frequency "smaller than twenty thousand per second", lowest frequency six per second, and a minimum wave-train duration of "0.08484 of a second" at a mean surface speed of 471,240 km/s, plus the explicit statement that the planet behaves "like a perfectly smooth or polished conductor of inappreciable resistance ... transmitting slow electrical oscillations without sensible distortion and attenuation" [read: PDF p.425]. The last statement is the assumption the worked example tests.
• arbiter.md, Claim 1, "What would settle it" (3): "The receiver frequency in the 4 July entry, to compute node spacing". Tesla himself gave the wavelengths of the waves he observed, in the 1905 "Reply to Edison": "from data obtained in a large number of observations of the maxima and minima of these waves I found their length to vary approximately from twenty-five to seventy kilometres" [read: Tesla Said p.95, via deep read]. This gives 4.3-12 kHz at light speed [calc] and should be cited beside the storm-speed estimate; the raw data behind it are still missing.
• primer.md (this file, earlier version), section 4.4 and the evidence table: "That is consistent with the second law" and verdict "Not refuted" for Tesla's 1900 sink text. Wrong. The earlier version quoted Tesla's caveat and stopped; the paragraph continues "less energy will be needed to maintain the initial condition than is developed by the fall ... what is converted is clear gain" [read: Century reprint p.21], a claim of partial net gain from one ambient reservoir, which the Carnot calculation rules out. The arbiter's QE revision (A) changes the verdict to Refuted by calculation; the Thermodynamics2 deep read (line 166) had flagged it. The earlier lesson that "later readers drop the caveat" is also corrected: Tesla argued the partial-gain version himself.
• primer.md (earlier version), section 7: "his diary was more cautious than his press articles ... the bold version appeared when he was raising money". Incomplete. The Notes of January 1900 say "The existance of stationary waves proves the feasibility of the project almost beyond any doubt" [read: Notes line ~18559]; the caution of 3-4 July concerned only where the waves were reflected.
• primer.md (earlier version), section 4.6: "no apparatus, drawing or parameter exists in any record found" (teleforce), and "released to Sava Kosanovic (1952 per a 1981 FBI letter)". The first is overstated: Trump's 1943 abstracts of Exhibits F, H, J and Q are written outlines with parameters (50 MV, 350 mi/s, 100 miles) [read: FBI 02 deep read]; no apparatus or test is on record. The second is not established: the FBI's two 1981 letters disagree with each other (arbiter QE revision D).
• primer.md (earlier version), sections 4.5 and 6: "29-52 per cent" and "14-52 per cent". Lowenstein's first test (53.4 lb/bhp-h) is about 25 per cent of ideal expansion by IAPWS-IF97 (arbiter QE revision E), so the band for Tesla's and his associates' tests is about 25-52 per cent. Stale copy: claims.md claim 5 still gave "about 27%" for this test (the QE figure from memory steam values); the arbiter's 24.6 per cent supersedes it. Fixed in claims.md (arbiter revision F).
• arbiter.md, QE revision B, "Cavity Q 'as high as 1000': weighed": "What each gives for a 7.8 Hz pulse over the 0.067 s round trip". The percentages (37, 58, 97, 99.7 per cent) are right, but 0.067 s is the one-way trip of 20 Mm to the antipode at light speed, not a round trip (the round trip is 0.134 s) [calc, example.py Step 3b]. Over a full round trip the energy left would be the square of each figure (14, 34, 94, 99.3 per cent). The conclusion does not change.
• primer.md (earlier version), section 6, "Where the record goes dark": "patent counsel Kerr, Page and Cooper called his patents 'controlling' and worth 'not less than $5,000,000'". Wrong. The 1904 file holds only Tesla's covering letter: "controlling" is his reading of an enclosed statement whose text is not in the scan, and the $5,000,000 is his own valuation [read: research/files/tesla-papers-1904-rankine-letters_djvu.txt lines 307-311; arbiter revision F9 item 1]. Corrected above.
• primer.md (earlier version), section 4.1 and the evidence table: the January 1900 lamps "sit at tens of feet from the primary", and "one to five lamps at about 60-100 ft". These merged two set-ups: the 1 January field lamps (ungrounded loop, about 60 ft, magnetic induction) and the 2 January table lamps (grounded coil, distance not stated in the Notes) [read: Notes lines 18209-18215, 18391-18459, 22520-22521]. Verdict unchanged. Corrected above.
• primer.md (earlier version), sections 4.7 and the Source gap: "a draft note/draft passage" (Notes line ~17149). It is the copy of an 8 December 1899 press statement to the North American [read: Notes lines 17127-17149]. Corrected above.
• primer.md (earlier version), section 7: "a peak rate during a few nanoseconds of discharge". Incomplete: that duration uses the primary condenser at an assumed 50 kV; Tesla's own 1916 antenna figures give about 0.3-0.4 microseconds [calc, arbiter revision F5]. Corrected above.