It was refreshing to read your six-part “Waverunner” articles on Nikola Tesla. While it's sad so many people have never heard of this incredible genius, it's also puzzling why many are still perpetuating untruths about him.

Calling Tesla the inventor of radio depends on what you call radio — whether it's simply wireless telegraphy or transmission of more complex information, such as sound. The activity was very cutthroat, and pirating abounded, as there were many people (including Tesla, Marconi, Sir J.A. Fleming, Lee DeForest, Fessenden, Popov, Slaby, Braun, and Stone) who were simultaneously working on radio. The consensus was that there was no single inventor, and it was more of a collaboration to which Tesla contributed.

Regarding Tesla's high voltage, high-frequency work, the first photograph of Tesla's conical coil in action appeared in the Century Magazine in April 1895 (issued about a month after his lab was destroyed by fire). The discharge was more like 3 and not 16 ft. Tesla had estimated the voltage to be 1 million V in the Electrical Experimenter, but this was not true.

After rebuilding his lab, he constructed a flat spiral coil 8 ft in diameter and introduced an “extra coil,” which was the first form of his magnifying transmitter. The first picture of this apparatus was published in the Electrical Review of October 26, 1898. Tesla reported the surface area of the discharge was about 200 ft2. Assuming this is a circle, it's easy to calculate the radius as being about 8 ft. He incorrectly estimated its voltage to be 2.5 million V.

Tesla originally intended to send a wireless message from Pike's Peak at Colorado Springs to Paris; I think he should have stuck with this plan or given a public demonstration of something less aggressive. He never created sparks as long as you reported. In his own notes at the time (Nikola Tesla Colorado Springs Notes 1899 - 1900), he describes photographs of his apparatus this way: “These streamers were about the longest producible in the present building, with the roof closed, measuring from 31 to 32 ft in a straight line from origin to end.” He speculates that considering the curved path, the length was probably double this (origin to end), and the tip-to-tip length of the spark would be double again, or 124 to 128 ft. Most Tesla historians agree this is where the false report originated. Tesla estimated the voltage of his Colorado Springs magnifying transmitter to be about 12 million V. Again, this is incorrect.

While a brilliant researcher and scientist, Tesla was a poor businessman, a big gambler, and prone to exaggerating the facts. Remember what happened to his lab in 1895? Once he was set up in Colorado Springs, why in the world didn't he publicly demonstrate what he had?
Bill Fox
Consulting Application Engineer (NEMA ac motors)
Siemens Energy and Automation
Norwood, Ohio