Tesla is vindicated: it turns out that this whole article was debunked in 1936, but the debunking was based on an error. Single-wire transmissions are not against EM theory after all! Zenneck surface waves had long been disproved, but since 2005 the disproof is now debunked again. See:
http://web.archive.org/web/20161019214341/www.texzontechnolo...
As a result, Corum's company "Viziv Technologies" has built a thirty-story plastic Tesla-tower out in Texas wilderness, and is now performing Earth-resonance experiments down at 12KHz broadcast frequencies. See tower construction slideshow:
http://amasci.com/graphics/st/