Archimedes and the Surface of any Fluid

Archimedes is a scientist from 3rd century BC. He is best known for the Archimedes’ Principle which explains buoyancy. He also contributed to many scientific discoveries and inventions.

But did you know that Archimedes explained the Archimedes’ principle using the spherical Earth model?

Archimedes wrote the Archimedes’ Principle in his writing “On Floating Bodies,” which is separated into two books. The first part explains what we call now the Archimedes’ Principle.

He divided his explanation into several propositions. In his second proposition he explained:

“The surface of any fluid at rest is the surface of a sphere whose center is the same as that of the earth.”

Then he continued to explain his principle in the following propositions using the mentioned spherical Earth model.


Archimedes wrote his books in ancient Greek. The following is several English translations of his proposition discussed here.

“Archimedes” by Eduard Jan Dijksterhuis:

“The surface of any fluid which is so located that it remains motionless will have the form of a sphere which has the same centre as the earth.”

“The Works of Archimedes” by Sir Thomas Little Heath:

“The surface of any fluid at rest is the surface of a sphere whose centre is the same as that of the earth.”

“The Genius of Archimedes” by S. A. Paipetis & Marco Ceccarelli:

“The surface of any liquid at rest is a spherical surface whose center point is at the center of the earth.”

We can conclude there’s practically a consensus, and we can rule out translation errors in this case.


The background of our illustration is the Archimedes Palimpsest. It is a parchment codex palimpsest, which was a 10th century Byzantine Greek copy of the work of Archimedes and other authors. It was overwritten by religious text in the 13th century. But some of the text is recovered using modern technology.

The copy of Archimedes’ writings is the faint text. And the legible text is the religious text. The green tint is an effect of the recovery method used by the University of Pennsylvania.