One of the greatest inventors of the ancient world was Heron Alexandrinus, aka Hero of Alexandria, who racked up an incredible 80 inventions throughout his lifetime in the first century CE.  One of Heron’s remarkable inventions was an early (and possibly the first) steam engine.  But one that we moderns might least expect is one that we seldom associate with the ancient world: the vending machine. Heron’s vending machine sold one thing: holy water.  He invented it in order to stop the theft of holy water from the temples.  The way it worked was you’d put a 5 drachma coin in a slot.  The coin would land on one end of a lever which, when depressed, would allow holy water to trickle out of a spout.  As long as the coin was balanced on the end of the lever, the water would keep coming.  The coin would remain balanced for a short while.  When it dropped off the lever, a counterweight was released, closing the spout and preventing anyone from tak...