How Archimedes scuppered a Roman fleet

With so much history and legend behind it, Sicily is high on my list of 'must go' places. Some seriously cool stuff happened there. It even manages to make maths palatable.
You know Archimedes? He was a Greek mathematician who hung out in Syracuse just before the dawn of Christendom.
The UK's Sunday Times reported last week that a scientist claims to have solved the mystery of how Archimedes used solar power to help destroy a dastardly Roman fleet that ambushed his home city in the 3rd century BC.
Legend has it that during Sicily's Siege of Syracuse, Archimedes used mirrors to create a 'death ray' that burned through the enemy fleet's sails, rendering each vessel limp and lifeless. 
However, Cesare Rossi, professor of mechanical engineering at Naples Federico II University in Italy reckons that, in fact, Archie invented a steam-powered cannon to annihilate the invaders.
So, instead of reflecting sunlight straight onto moving ships, he might have used mirrors to heat huge kettles of water to power his prototype artillery. Rossi says curved mirrors could have concentrated the sun's rays on a tank filled with water. The water would have boiled and the trapped steam fired the gun, shooting flaming cannonballs at the Romans. And all this 1500 years before gunpowder was known in Europe. 
The paper says: 'Rossi calculated that a heated cannon barrel would need to have converted little more than an ounce of water into enough steam to hurl a 13lb projectile, with a firing range of 500ft. In the 15th century Leonardo sketched a steam cannon which he credited to Archimedes.'
I am no scientist, but the creative in me loves this story, whichever version of events - legend or logic - happens to be true.