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"As far as I know, it is the first paper about that use of a steam cannon by Archimedes," Rossi told LiveScience. That allowed the cannons to possibly target troops or ships at distances of approximately 492 feet (150 m) while firing at a fairly flat trajectory to make aiming easier. Rossi calculated that such cannons could have fired a cannonball weighing roughly 13 pounds (6 kilograms) at speeds of roughly 134 miles per hour (60 meters per second). The Greek-Roman physician and philosopher Galen similarly mentioned a burning device used against the Roman ships, but used words that Rossi said cannot translate into "burning mirror." Indirect evidence for the steam cannon also comes from the Greek-Roman historian Plutarch, who tells of a pole-shaped device that forced besieging Roman soldiers to flee at one point from the walls of Syracuse. Italian inventor Leonardo da Vinci sketched a steam cannon in the late 15th century, which he credited to Archimedes, and several other historical accounts mention the device in connection with Archimedes.

A heated cannon barrel would have converted barely more than a tenth of a cup of water (30 grams) into enough steam to hurl the projectiles. The steam cannons could have fired hollow balls made of clay and filled with something similar to an incendiary chemical mixture known as Greek fire in order to set Roman ships ablaze. No contemporary Roman or Greek accounts tell of such a mirror device, however.īoth engineering calculations and historical evidence support use of steam cannons as "much more reasonable than the use of burning mirrors," said Cesare Rossi, a mechanical engineer at the University of Naples "Federico II," in Naples, Italy, who along with colleagues analyzed evidence of both potential weapons. But new research suggests he may have used steam cannons and fiery cannonballs instead.Ī legend begun in the Medieval Ages tells of how Archimedes used mirrors to concentrate sunlight as a defensive weapon during the siege of Syracuse, then a Greek colony on the island of Sicily, from 214 to 212 B.C. Greek inventor Archimedes is said to have used mirrors to burn ships of an attacking Roman fleet.