Interactive graphic: A steam cannon with mirrors
Did the ancient Greek inventor Archimedes build a solar-powered steam cannon that fired flaming projectiles? That鈥檚 the suggestion of an Italian engineer who has come up with a design for such a weapon.
is said to have built fantastic machines of war, ranging from catapults to giant claws, that were used against the Romans during their , Sicily, in the third century BC.
Advertisement
One of the most controversial stories is that Archimedes set fire to Roman ships by focusing the sun鈥檚 rays onto them with concave mirrors. Sceptics say it would be impossible to use mirrors to keep the sun鈥檚 rays focused on a moving ship. What鈥檚 more, they say, the fires would start slowly and could easily be put out by those on board.
Now of the University of Naples Federico II suggests an alternative scenario.
He points out that several scholars, including and Leonardo da Vinci, wrote that Archimedes invented a cannon which used pressurised steam to force a projectile out of the barrel at high speed. In 2006 a team at the Massachusetts Institute of Technology .
Smoke and mirrors
Rossi reckons that steam cannon could explain the mirror legend. He suggests that such a cannon could have been heated by sun-focusing mirrors, while the projectiles would have been hollow and filled with an incendiary fluid 鈥� perhaps a mixture of sulphur, bitumen, pitch and calcium oxide. Rossi has worked out a possible design for the cannon.
Although using mirrors in this way might seem impractical, Rossi says it would have made sense for the Syracusans to avoid using open fires as the cannons would have been positioned on the city walls, on platforms made of wood.
Rossi calculates that a cannonball measuring 20 centimetres across would have weighed around 6 kilograms and could have been fired from the gun at 60 metres per second. A gun positioned 10 metres above sea level and firing at an angle of 10 degrees to the horizontal would have had a range of around 150 metres.
Historians who specialise in ancient technology say his idea is entertaining, but they doubt if anything similar was ever built.
of Birkbeck College, University of London, says there is no convincing evidence that Archimedes used steam cannon.She says that Archimedes鈥檚 fame in medieval times led da Vinci and other scholars to attribute any impressive inventions they heard about to him. 鈥淎rchimedes became a quasi-mythical icon of the scientist capable of constructing incredible weapons,鈥� she says.
Tracey Rihll at Swansea University, UK, notes that Rossi doesn鈥檛 explain why the hollow clay cannonballs didn鈥檛 break apart when they were fired. Catapults would be a more practical way of hurling flaming projectiles, she says.
Reference: (Eds: S. A. Paipetis and Marco Ceccarelli, Springer)
When first posted, this article incorrectly stated that Serafina Cuomo was at Imperial College London.
