Archimedes of Syracuse was a Greek mathematician and scientist. He discovered the value of “pi” by which the area of a circle could be accurately calculated. He invented several machines, including a water-turning screw to draw water upwards without individual buckets or lengthy ropes.
He invented a giant lens antisiege machine to focus the sun’s rays onto a single point to set enemy ships aflame.
When the Romans invaded his city he was engrossed in drawing mathematical designs on the sand. An officer gave orders that he was to be found and captured alive. But a solider, not knowing who he was or what he looked like, killed him when he did not obey a command to stand up from his work.
One Famous story is that he was granted a task by the king of his city. The King had commissioned a royal crown to be made out of pure gold, and had given enough gold from his treasury for the task to a craftsman. The king, upon taking the finished crown, suspected that the craftsman had mixed the crown with another metal and kept some of the gold for himself, but didn’t know how to prove it.
The King asked Archimedes to find a way to test whether the crown was pure gold or not without damaging the crown.
Archimedes pondered the task for several months, and obsessed about it so much that he neglected his personal hygiene and began to stink. His friends, in an act of desperation, intervened and dragged him to the public bathes. As he sank down into the bath, Archimedes notices that his body displaced a noticeable amount of water.
He realized that the density of an object displaced an equivalent amount of water. Thus, by knowing the density of gold, and the amount of gold the crown should have been made from, he could calculate whether the crown was made entirely of gold or not.
He jumped up from the bath and ran home, quite naked, shouting “Eureka!” (in greek, meaning “I’ve got it” or “I’ve found it.”