He discovered it.
Yes
Archimedes
Who was Archimedes.
Displacement.
Archimedes
He figured out the displacement method.
They are both the same. displacement method is another name for Archimedes' principle
Archimedes stated that the mass of liquid displaced by a floating body equalled the mass of that body. One can deduce from this that if the displacement is less than the mass of a body then that body will sink.
Archimedes
If you are talking about water displacement, it is the Greek philosopher Archimedes who is credited with that.
Archimedes was generally considerd to be the great mathmaticians of antiquity he spend his most of the time in Egypt where he invited the machine called Archimedes screw he was born in Greek in 365 BC
Archimedes discovered the concept of gravity with his levers and pulleys, his theory of displacement and invented the screw.