Heron's Aeolipile: Why Was Steam Power Kept as a Demonstration?

Around the first century CE, in Alexandria in Roman Egypt, the engineer Heron described a device called an aeolipile. A boiler sent steam into a hollow sphere. Steam escaped through bent tubes on its sides and made the sphere rotate. The device showed that steam could create rotary motion. It was not yet a piston engine for driving a pump or a loom, although many histories call it a precursor of the steam engine.

In 1698, Thomas Savery patented a machine that used steam to raise water. In 1712, Thomas Newcomen put a piston and cylinder engine to work at a coal mine in England. James Watt improved the Newcomen engine from 1765 onward. Steam later drove pumps, factories, ships, and locomotives. More than 1,600 years separated Heron's sphere from those machines.