Combustion Visualised.

The steam locomotive is a heat engine—heat being its one and only source of power. The theory of combustion is the understanding of heat generation and transfer.

Combustion is a chemical combination or reacting that produces heat, and heat is a form of energy due to molecular vibration or motion.

To understand this we must try and get a mental vision of the processes of chemical combination and we must be able to picture a structure of matter that is capable of molecular vibration. We will endeavour to do this as simply as possible.