translation.en: And then Robert Stirling came along with this genius idea, which was, well I'm still not heating the metal now, with this kind of engine, but I'm still reheating all the air.
translation.zh: 这个聪明的设想是有Robert Stirling 提出的， 不加热金属部分了现在， 但是在这种引擎里，我还得从新加热所有的空气。