Archimedes had many inventions and is regarded as one of the greatest mathematicians of all time. In general, he is historically known for a wide range of contributions. Here are two that bear his name.
The Archimedes screw or screwpump, which looks somewhat like a drill, is a machine designed to take water from lower level water supplies into irrigation ditches; it could also remove bilge water from a ship. It is attributed to Archimedes following his trip to Egypt.
He also came up with what is known as Archimedes' principle which he states, "Any floating object displaces its own weight of fluid." In terms of displacement and buoyancy, it can be stated, "Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object." Perhaps a simpler way of explaining it is this. Say you weigh 100 pounds and you lower yourself into the water, displacing 30 pounds of water. Now, in the water, you weigh 70 pounds. The weight of water you displace buoys you up with the same force.