His first discussion is about a machine that can gather heat from the ambient air. He calls it a “Self-acting Engine” since it could run indefinitely from the solar energy stored in the air. He called it “the ideal way of obtaining motive power”...
He is talking about a sterling engine, they are used in some commercial scale solar electric generation stations. they work on temperature differentials. You can buy a model that you can build at home. my brother had to build one as part of his mechanical engineering degree from MIT. Goddard built a working solar power unit prior to 1920.
we know a lot about the sun.
https://en.wikipedia.org/wiki/Sun
tesla's electricity would have been free of charge, not "free energy" in the perpetual motion machine sense.
I won the science fair twice, once was with my tesla coil and the other was with my pickle light based on quantum physics.
The geet engine and perpetual motion free energy machines are impossible under both classic and quantum physics.
RE: Is The Oil Industry Suppressing Alternative Fuels? We can run an engine on tap water!