Nikola Tesla Books
U. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS BOULDER LABORATORIES BOULDER, COLORADO CRYOGENIC ENGINEERING LABORATORY CENTRAL RADIO PROPAGATION LABORATORY RADIO STANDARDS LABORATORY August 25, 1959 IN REPLY REFER TO FILE NO. 85.60 AIR MAIL Mr. Leland I. Anderson 1615 East River Terrace Minneapolis, 14, Minnesota Re: Your letter of Feb. 21, 1959. Dear Mr. Anderson: As a result of the pressure of work at this laboratory, I must apologize for this slow reply to your letters. I have read the papers on Tesla's experiments [1,2] at Colorado Springs, which experiments seem to indicate the presence of standing waves resulting from the propagation of electro- magnetic pulse radiation from thunderstorms. Unfortunately, I could not find sufficient information on the experimental details to reach any definite conclusions about these apparently observed standing waves. However, there are various highly speculative possibilities which I can suggest as a possible explanation. Perhaps the most significant and remarkable point about the Tesla experiment was the observation of a standing wave of 47 km length (λ = 47,000 meters). I note this wavelength corresponds to a frequency (f = c/λ, c ~ 3 (10⁸) meters/second) of 6.4 kilocycles (which value ranged from 4.3 kilocycles to 12 kilocycles according to the Tesla data). Recently, I have analyzed numerous sferics in accordance with the general approach presented in my paper [3] (copy enclosed) eqs. (45-52). The spectrum, Fₓ (ω, d), eq. (45), and in particular, the amplitude spectrum, |Fₓ (ω, d)|, is of particular interest in this experiment. A particular sferic (electric amplitude vs. time waveform of the electro- magnetic pulse radiation of a lightning stroke) was observed and recorded on "high fidelity" receiving equipment as an oscillogram (copy attached), Re E (t', d). The sferic was apparently radiated from a cloud to ground
