information:extraction, linguistic:voice_change
Machines

The work is important for its descriptions of the many different machines used for engineering structures such as hoists, cranes and pulleys, as well as war machines such as catapults, ballistae, and siege engines. As a practising engineer, Vitruvius must be speaking from personal experience rather than simply describing the works of others. He also describes the construction of sundials and water clocks, and the use of an aeolipile (the first steam engine) as an experiment to demonstrate the nature of atmospheric air movements (wind).