The Greek inventor Archimedes is said to have burned the ships of the attacking Roman fleet by focusing and directing sunlight with mirrors. However, a study by Italian scientists proves that he used steam cannons and fireballs instead.
A legend spread throughout the Middle Ages tells how Archimedes, during the siege of Syracuse, a Greek colony in Sicily, from 214 to 212 BC used mirrors concentrating sunlight as a defensive weapon. However, none of the evidence from Roman or Greek contemporaries of those events mentions such an ingenious device.
In the artist's view, something like this Archimedes led the defense of Syracuse.
Technical calculations and historical evidence confirm that the use of steam cannons is "much more sensible than the use of reflective mirrors," says Cesare Rossi, a mechanical engineer at the University of Federico II in Naples, Italy, who, together with colleagues, analyzed evidence of the use in combat conditions of both potential weapons.
Steam cannons could fire hollow balls of clay filled with a burning mixture known as Greek fire to set Roman ships on fire. A heated gun barrel would convert just over a tenth of a cup of water (30 grams) into enough steam to fire projectiles.
Use of steam energy
At the end of the 15th century, the Italian inventor Leonardo da Vinci developed a steam cannon, which Archimedes could have created long before him, and indeed in several historical accounts this device is mentioned together with the name of Archimedes.
Promotional video:
Steam cannon of Archimedes, drawing by Leonardo da Vinci, Volume II.
Circumstantial evidence for Archimedes' creation of a steam cannon also comes from the Greco-Roman historian Plutarch, who tells of a rod-shaped device that forced besieging Roman soldiers to flee away from the walls of Syracuse.
The Greco-Roman physician and philosopher Galen also mentioned a device that spewed fire against Roman ships, but used terms that, according to Rossi, cannot be translated as "burning mirrors."
Schematic diagram of the Archimedes steam gun.
Rossi calculated that such guns could fire cannonballs weighing about 6 kg at a speed of about 60 m / s. This allowed the cannons to potentially finish off ground forces or ships at a distance of about 150 m when fired on a relatively flat trajectory to facilitate aiming.
Previous research by the Greek engineer Joannis Stakas and the historian Evangelos Stamatis showed that small wooden ships can indeed be set on fire with a parabolic mirror. A similar demonstration was carried out more than three decades later, in 2005 by researchers at the Massachusetts Institute of Technology.
However, Rossi wonders whether the mirrors could maintain an ever-changing curvature in order to maintain the correct focus to maintain combustion on moving ships. He adds that ancient sailors could easily extinguish such a fire, or avoid it altogether, simply by keeping the ship in motion.
On the contrary, many historical accounts indicate that Greek fire was a deadly threat to ancient warships. An unknown chemical compound supposedly burned even under water and was most widely used by the Byzantine Empire, which dominated the eastern Mediterranean from 330 AD. Other records mention earlier versions of the burning mixture.
Change the past
Steam cannons aren't Rossi's only historical study. He previously worked with military historians Flavio and Ferruccio Russo on Inventions: Precursors of the Present (Springer, 2009).
The trinity of researchers plans to meet with other historians and possibly reconstruct ancient weapons. Flavio has previously performed several reconstructions of ancient Roman artillery, and Ferruccio specializes in virtual 3D reconstructions of mechanical devices.
Several of Rossi's works are devoted to ancient engines that could move the siege towers of the Greeks and Romans. The most probable engines may have been based on counterweights and appeared in the first century as an invention of Heron of Alexandria.
Siege tower of Gelepolis. Reconstruction by Flavio Russo.
According to Rossi, such devices could be built into the structure of the towers themselves. He refers to the notes of Julius Caesar, who spoke about the use of such towers against the city, which was defended in the territory of modern France by the Gallic tribes. The sight of the towers, which seemed to move on their own, frightened the defenders so much that it forced them to beg for surrender.
Examples of antique * engines *.
In the end, Archimedes' engineering talents did not save him from death when the Romans took Syracuse by storm. But at least a love of the history of Rossi and his colleagues could lead to a revival of some of the remarkable devices of ancient Greek genius.