How Archimedes Burned Those Roman Ships: Mirror or Steam Cannon?

By Joseph Calamia | June 28, 2010 11:00 am

mirrorHere’s the situation: You spot Roman attack ships headed for your shores. Do you order your troops to ready the cannons? Or–in an ancient MacGyver move–do you use a parabolic mirror, focusing the sun’s rays to set the ships on fire? Though the latter is clearly more suave, recent research has shown that the 212 B.C. legend about Archimedes’ mirror defense is unlikely: He probably pulled out the big guns instead.

Cesar Rossi, a mechanical engineer at the University of Naples in Italy, figured out the numbers. A steam cannon–like the ones Leonardo da Vinci drew in the 1400s–could use less than a tenth of a cup of water to fire a hollow clay ball, at 134 miles per hour, to hit a target 492 feet away. For comparison, an 1854 American Civil War Howitzer cannon could fire a ball about ten times farther–a little less than a mile.

Rossi presented this research at the International World Conference in Syracuse, Italy (the site of the historic Roman attack on the Greek colony) earlier this month. He told LiveScience that after looking at both the historical references to the battle and the feasibility of using the mirrors on moving ships, that the cannons were “much more reasonable than the use of burning mirrors.” The hollow clay cannon balls could have been filled with a mix of incendiary chemicals that would have set the ships afire on impact, Rossi suggests.

In 2005, MIT students recreated the mirror defense and managed to set a wooden “ship” ablaze. On the roof of a Cambridge parking garage, they scorched the ship, but their test required ideal weather conditions and a stationary target. Rossi hopes to team up with other researchers to create his own reenactment using the steam cannons.

Cannons or mirrors, Archimedes couldn’t save Syracuse–and the Romans’ success meant Archimedes’ end.

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Image: Wikimedia / Giulio Parigi, 1600

  • Richard Dinning

    The Mythbusters TV program tried to do this and even with a stationary mirror and a “ship” only a few metres away, the best they could do was some scorching.

  • Laurie Penman

    I wonder why Mr. Rossi limited himself to a quarter of a cupful of water. Given the Greek expertise with bronze, I would have thought that a vessel containing steam at 5 psi could be opened into a 12″ diameter tube and project a hollow clay ball of 25 pounds weight at just over 4g, or a more massive one of 50 pounds at more than 2g. The latter would have a better chance of a decent range, of course, but if that was less than 500 feet a more traditional weapon is much faster in use and, I would have thought, more accurate.

    Given Archimedes work with levers, would a counter-weighted lever (trebuchet) be too fanciful? The details of his other weapons have mostly disappeared, a trebuchet is so removed from contemporary experience that any remains could easily be unrecognised as a weapon and be lost to history, but it has a staggering range with large projectiles, which would arrive out of a brilliant Syracusean sky. How many victims would see it as it plunged into their vessel? It is unlikely that any combatant would be looking skyward and the destruction would be credited to anything but a trebuchet.

  • Jennifer Ouellette

    Depending on which historical account you consult, the ships may have actually been anchored. Still, mirrors as “death ray” definitely not an efficient weapon…

  • Rebecca Horne

    I love this. Hoping to hear the follow up about the cannon tests.

  • Joseph Calamia

    Richard, thanks for mentioning the MythBusters attempt. Definitely something to add to my Netflix…

  • Barbara

    I wonder if they tried setting the sails on fire, instead of the ship itself. Seems that if the sails got going, they could easily set the rest of the ship on fire.

  • Italoboy

    ”Cannons or mirrors, Archimedes couldn’t save Syracuse–and the Romans’ success meant Archimedes’ end.”

    Symbolic end of all good things Greek: insatiable curiosity about Nature and quest for Truth, and all bad things Roman: imperialism, empire-building, administration. bleh.

    Shame the Greeks didn’t win.

    Italoboy (A.G. lover)

  • Steve

    Concave Mirror, which focuses the light into a smaller area, (highly polished shield turned around) with a lens fixed to the shield by an iron rod maybe an arms length distance, to focus the light again, I’d say it was possible, and well within the skill range of the ancient greeks.


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