Heron , yeah of the high school Hero’s Formula fame invented this crude form of modern day Steam Engine. 1600 years down the line after his invention did people realize the importance of this much neglected toy made by Hero (of Alexandria, 1 AD). I never knew that something of this nature was thought before Steam Engine was invented (which marked the beginning Industrial Revolution in Europe). Sad that he isn’t given the credit.
What is Aeolipile ?
The word means “Wind Ball” in Greek. What hero did was very simple. Take a closed vessel , fill it with water. Heat it.Now what do we have , Steam of course. Let it pass through two vertical outlets into a Ball which can rotate. To create a torque on this Sphere (which has to be fixed so that it can rotate about the pivot). Place two vents opposite diametrically and lo ! the ball will rotate due to the torque generated.
No Rocket Science , You’d say ! But that’s the same principle behind today’s Rocket !!! Aint’t it ? 
. Beautiful conversion of Thermal Energy to useful mechanical Shaft rotation.
Hats Off ! Mr Heron !
Hero apparently did not use it much ; It was a more of a fancy toy , says history . Sad. Some articles on the net say he used it to open doors at Temple (How ?! and Why Temple doors ? ). This is the same principle behind the steam engine.
A step by step procedure to create Heron’s Aeolipile is available at this link ( I did not really have the patience to go through it 
Call it the initial poor “oh this is so simple for me” attitude) : http://www.instructables.com/id/Ancient-Aeolipile–steam-engine%2c-and-magnets-for-g/
Complete detailed Analysis which I plan to study soon is available at http://www.mlahanas.de/Greeks/HeronAlexandria.htm Here’s a nice video . How I wish we could do projects like these at school instead of boring theory !
