Steam machine

This model of a triple expansion machine is the most recent form of the traditional steam machine. Steam machines appeared in ca 1807, but were not widespread until 1860. Its two key elements are: the boiler, that produces the steam, and the machine, which transforms the steam into mechanical energy. They turn at a rate of 20 turns per minute to operate paddle wheels, more often than propellers. The propulsion by paddle wheels, then by propeller, was not suitable for small boats: the steam machine was too big for them. The steam engines were little by little replaced by diesel engines.