Archimedes was a close friend of King Hieron. King Hieron had ordered a gold crown to be made. When the goldsmith brought the crown it felt very light. The king asked Archimedes to find out whether the goldsmith had cheated or not by comparing the weight of the gold and the weight of the crown. Accidentally he found out that if a body is put in water, it displaces a volume of water equal to the mass of the body. This way he found out that he could measure the volume of all irregular solids. He thus put the gold crown and solid gold of equal mass in water. The crown displaced more water and thus had larger volume. Which signified that the crown had silver as silver displaced more water than gold. And they found out that the goldsmith had cheated on them.