Firstly, any idiot can be granted a patent. All you need to do is make up a new device, it doesn't have to have any use to society at all. For example, I could patent the design to a 4 blade knife I make up if its design is different than any other knife. But will anyone use such a thing? No. Secondly, I bet all of his inventions were really not invented by himself as was the air conditioner.