The next subject in our series is the engine.
What is an engine? An engine is a device that can convert energy into motion. Engines have been around for a long time.
One of the first writers to describe an engine was Hero of Alexandria, who lived in the first century C.E. He wrote about a device called an aeolipile, also called a Hero engine.
The Hero engine runs on steam power. Its simple design consists of a cauldron, or a large metal pot, on legs. The cauldron is filled with water, and a cover is placed on top. A hollow metal sphere is then connected by pipes to the cauldron. The ball has two L-shaped tubes protruding from opposite sides and facing opposite directions. When the water in the cauldron is heated, steam escapes through the pipes to the metal sphere, and from there is forced through the tubes. This causes the sphere to rapidly spin around.
Interestingly, it seems that no practical use was found for the aeolipile. It was just displayed to watch it spin! Nevertheless, the Hero engine is considered to be an early predecessor to the steam engine.