Identify this invention which is widely used across the globe in its modernized avatar. (Hint: Think ancient)
Ans.: Vending Machine. The first recorded reference to a vending machine is found in the work of Hero of Alexandria, a first-century engineer and mathematician. His machine accepted a coin and then dispensed a fixed amount of holy water. When the coin was deposited, it fell upon a pan attached to a lever. The lever opened up a valve which let some water flow out. The pan continued to tilt with the weight of the coin until it fell off, at which point a counter-weight would snap the lever back up and turn off the valve.