(Actually nowadays you really can easily google that old book and read the amusing proof for yourself, but for a long time that wasn't an option.)
that's pretty interesting, I wasn't aware of that. i wonder if there is a fad element to it. The reason why I mentioned the "decide for yourself" is that I've ran into that so often on youtube videos in recent years. But now you mention that book, I recall back in the day, when i was a teenager and a friend got me interested in conspiracy theories, there definitely was the hidden knowledge angle regarding all the free-energy related discoveries by Nikola Tesla that few if any could ever replicate. A big name in that field was Tom Bearden. At a temp job I had, I ran into a guy with a common interest, who claimed to have been working with a physicist in his garage who was building a free-energy device. He offered the name Henry Moray (a Mormon even), who I had heard about, but he said a big secret for tuning a tesla coil right to achieve free energy, was in this book he'd written that was nearly impossible to get. He claimed to have ten copies of the book and declined to let me borrow one. So I went to the biggest and baddest used bookstore around and put a hold on that book should one come in. Years later my parents got a call about one coming in but I'd moved on. Pretty sure it's available to anyone now.