I am composed of copper, and I am heated by means of the same metal, so that you may

I am composed of copper, and I am heated by means of the same metal, so that you may have the benefit of the copper, either to heat or to cool any other body, and I am composed of iron, so that you may have the benefit of the iron to produce magnetism, and I partly heat, and partly cool the copper, and I partly heat, and partly magnetise the iron, and partly heat the wood, to which you are to trust for the