Here is a very Tesla-esque unexplained phenomena: an electrostatic force field.
<a href="http://amasci.com/weird/unusual/e-wall.html">http://amasci.com/weird/unusual/e-wall.html</a>
David Swenson of 3M Corporation describes an anomaly where workers encountered a strange "invisible wall" in the area under a fast-moving sheet of electrically charged polypropelene film in a factory. This "invisible wall" was strong enough to prevent humans from passing through. A person near this "wall" was unable to turn, and so had to walk backwards to retreat from it.
The production manager did not believe Mr. Swenson's report of the strange phenomena. When they both returned to the factory floor, they found that the "wall" was no longer there. But the production workers had noticed the effect as occurring early in the morning when humidity was lower, so they agreed to try again another day. The second attempt was successful, and early in the morning the field underneath the "tent" was strong enough to raise even the short, curly hair of the production manager. The "invisible wall" effect had returned. He commented that he "didn't know whether to fix it or sell tickets."
An article about Tesla's Teleforce from the NY times 9/22/1940
<a href="http://teslaresearch.jimdo.com/articles-interviews/death-ray-for-planes-new-york-times-september-22-1940/">http://teslaresearch.jimdo.com/articles-interviews/death-ray-for-planes-new-york-times-september-22-1940/</a>
The beam, he states, involves four new inventions, two of which already have been tested. One of these is a method and apparatus < section not legible eliminating the need for a "high vacuum;" a second is a process for producing "very great electrical force;" third is a method of amplifying this force, and the fourth is a new method for producing "a tremendous repelling electrical force." This would be the projector, or the gun of the system. The voltage for propelling the beam to its objective, according to the inventor, will attain a potential of 80,000,000 volts.
With this enormous voltage, he said, microscopic electrical particles of matter will be catapulted on their mission of defensive destruction. He has been working on this invention, he added, for many years and has made a number of improvements on it.