Steam Engine

The earliest known application of using steam to produce mechanical work was developed by Hero of Alexandria in the beginning of the first century.[3] His apparatus was called the aeolipile (also know as Hero's Engine) and is illustrated on the right. The basic operation of the machine used a cauldron covered with a lid placed over a fire. Above the cauldron two bent pipes ran up to a ball that could rotate. Two more bent pipes were connected to the middle of the ball and released steam directionally to apply a rotational force on the ball. The water boiling up through the ball being released through these pipes produced enough pressure to rotate the ball, thus converting steam to mechanical energy. [4]

After Hero's discovery steam powered devices were studied extensively, but it was not until the early 18th century that a practical device was created to harness the mechanical energy produced by steam. In 1712 Thomas Newcomen developed the first practical steam powered engine that produced useful mechanical energy.[5] As strange as it seems, the engine's main purpose was actually to pump water! The basic premise uses a weighted lever to pull a piston upwards and a vacuum created by condensing steam to bring it back down. The pumping rod (left) is heavier than the piston and so it pulls the piston up, filling the cylinder with steam. Once the piston reaches the top of it's stroke cold water is injected into the cylinder, this condenses the steam and creates a partial vacuum. This vacuum pressure pulls the piston back down until the valve to the boiler is opened again. Steam restores the pressure in the cylinder as the weight of the pump rod drives itself back down, repeating the cycle. This machine could opperate at 12 cycles per minute! Automations were continually added such as powering valves and switches with steam. The machine was later improved by the well known scientist James Watts who added a regulator (centrifugal governor) and other attachments to increase the overall efficiency.[6]