Why do ships float on water when in fact they should sink? Why does paper float on water and a paperweight sink? The answer to these questions was accidentally discovered 2200 years ago by the Greek inventor and mathematician, Archimedes.
One day, while getting into his bath he noticed water spilling over the sides. In a flash, Archimedes realised the relation between the water that had fallen out and the weight of his body – in other words he discovered why some objects float and some sink! Archimedes was so excited with his discovery that he hopped out of the bath, and rushed naked into the street yelling triumphantly, ‘Eureka!’ ‘Eureka!’ (Greek word for ‘I have found it!).
Archimedes discovery, now popular as the Archimedes’ principle, explains why steel ships, weighing thousands of tons, float. But what is Archimedes’ principle? When a body is immersed in water, it experiences a force (known as the buoyancy force).
This force is equal to the weight of the water displaced by the body. For instance, a lump of steel will sink for it is unable to displace water that equals its weight. But steel of the same weight but shaped as a bowl, will float. This is because the weight gets distributed over a larger area and the steel displaces water equal to its weight. So a heavily laden ship floats because its total weight is exactly equal to the weight of the water it displaces. It is this weight that exerts the buoyant force supporting the ship.
Archimedes is also known for his extensive work in geometry; and the invention of the lever and pulley. He also created a range of mechanical devices for the defense of his homeland – the catapult and a mirror system (for focusing the sun’s rays on an enemy’s boat causing it to catch fire).
In a rare find, scientists have recently managed to unearth a manuscript, the only surviving copy that contains Archimedes’ theory of flotation and some mechanical theorems. Particularly interesting is the fact that in many parts of the manuscript, Archimedes gives detailed explanations using diagrams. Researchers now hope to get a valuable insight into how Archimedes’ mind worked and how he went about devising his abstract theorems.
According to historians, Archimedes probably wrote his manuscript on papyrus scrolls, fragile in nature. About a 1,000 years later, the documents were copied onto leather sheets and bound into a book form, to prevent their deterioration.
In the Middle Ages about 1000 years ago, in Europe, Christian monks frequently recycled parchment works. The contents of the parchment held little interest for the monks, but they needed writing materials, so they tore apart the original manuscript.
The writing was erased by scraping the skin and the pages were cut in half and recycled into a Christian book of religious instructions. The new words were written sideways across the original text. Such works became known as ‘palimpsests’ (Greek for ‘scraped again’). The manuscript that is currently under study at a university in New York is called the Archimedes Palimpsest.
For 700 years, it remained in Palestine and Constantinople, cities that were once centers of learning. In 1906 a Danish scholar discovered the barely legible original text underneath. The book disappeared again around 1920 only to surface in an auction house as recently as 1998.
Now scientists are piecing together the cut pages and are using ultraviolet and infrared filters to capture images of the original words. Both infrared and ultraviolet light penetrate the surface text and get reflected. The reflected text is recorded on camera and reveals details that aren’t evident to the naked eye. The job is quite complicated, but scientists hope to decipher the writing soon.