The water overflowed when Archimedes jumped in and he knew that there is a relationship between his weight and the volume of the water
You can use the formula for a cylinder in this case.
there are 2 ways that I know about: the first way is length x width x height. And the second way is the water displacement method by Archimedes.
The conclusion of the Archimedes principle is simply that the upward buoyant force that is experienced by a body immersed in a fluid, is equivalent to the weight of the fluid that the body displaces. This allows the volume of an object to be measured by measuring the volume of liquid it displaces after submerging. For any immersed object, the volume of the submerged portions equals the volume of fluid it displaces.
Legend says that Archimedes discovered the principle of displacement while stepping into a full bath. He realized that the water that ran over equaled in volume the submerged part of his body. Through further experiments, he deduced the above mentioned Archimedes' principle.
Archimedes
215bc
He discovered that you have to find the volume, mass, and density of something
How? With his brain! That's how he answered it
He discovered the method to calculate the volume of a irregular object (rock).
Archimedes
Archimedes took a bowl full of water of known volume and then dipped the irregular shape body. Amount of water fall down is measured and is the volume of that body.
he find that the water was risen where he stared to put the person in.
Water displacement is used to find the volume of irregular solids as discovered by Archimedes
Archimedes discovered that all substances have a unique density - the amount of mass contained in a fixed volume of the substance.
Archimedes
Presumably during his life time and the volume in cubic units = 4/3*pi*radius3