Hero of Alexandria (c. 10–70 AD) Hero (or Heron) of Alexandria was an ancient Greek engineer, mathematician, and inventor who lived in Roman Egypt. He is considered one of the greatest mechanical engineers of antiquity, and his ideas were centuries ahead of his time. --- 🔹 Hero’s Inventions and Contributions 1. The Aeolipile (Steam Engine) – The First Reaction Engine This was a simple steam-powered rotary device, often called the first-ever steam engine. It consisted of a hollow sphere with bent nozzles, and when heated, steam escaped, making it spin. Although it was never used for practical work, it proved the principle of reaction propulsion, which is the same principle behind jet engines and rockets today. --- 2. Automatic Doors – First Use of Steam Power for Automation Hero designed a system where temple doors could open automatically using steam pressure! The mechanism involved heating water to produce steam, which moved a piston and pulled open the doors. This was one of the first automated mechanical systems ever recorded. --- 3. The First Vending Machine He invented a coin-operated vending machine that dispensed holy water in temples. When a coin was inserted, it triggered a lever that opened a valve, releasing a small amount of water. This was one of the earliest examples of automation and mechanical engineering in daily life. --- 4. Wind-Powered Machines Hero described a wind-powered organ—an early example of using wind energy for automation. This was an early version of the windmill, which became widely used centuries later. --- 5. The First Programmable Machine (Mechanical Theater) Hero built an automated puppet theater that could perform plays using mechanical systems. It used ropes, pulleys, and weights to move puppets in a precise sequence—like an early robot or mechanical programming. This was one of the earliest examples of automation and robotics! --- 6. War Machines and Siege Devices Hero improved designs for catapults, ballistae, and other war machines used by the Greeks and Romans. He also invented a primitive fire hose that used air pressure to pump water—similar to modern fire-fighting equipment ---