Archimedes fire-mirror gets an early bath

Jona Lendering points out that the common story that Archimedes used mirrors to set fire to Roman galleys rests on, erm, no historical source earlier than half a millennium later.  He lists the data and concludes the whole story is a legend.  Very interesting indeed, and highlights the need to tabulate the data before evaluating it.

7 thoughts on “Archimedes fire-mirror gets an early bath

  1. This particular issue is discussed at length by Christos Lazos in his book “Αρχιμίδης, ο ευφυής μηχανικος” (Archimedes, the intelligent engineer). Sources for Archimede’s life are fragmentary at best anyway, that Plutarch does not mention it in the life of the Roman general who was besieging Syracuse is not a surprise. Tzetzes gives a very detailed description of the mirrors that Archimedes used and in 1972, using Tzetzes description a Greek scientist burned a boat in Eleusis harbor using sunlinght. The fact that Pausanias description of the sinking of Helice also dates 5 centuries after the event does not reduce its historicity. The largest survivng part we have from Manethon is from Gerogios Syncelleus who wrote his book 11 centuries after Manethon. There is no real reason in my mind to doubt what 8 different Byzantine writers confirm, especially since it has been experimentaly verified

  2. I have managed to locate a thesis on Archimedes (in Greek) on the web and here are a few original sources:

    * Anthemius of Tralles (Architect of Hagia Sophia), Concerning wondrous machines (ca 474-558 AD)

    * Dio Cassius, Fragment of book 15 (from Ioannes Zonaras, who also mentions Proclus)

    * Galen, De temperamentis libri

    * Eustathius of Thessaloniki, Commentary on Homer

    * Tzetzes : Book II line 118 – 128:

    When Marcellus withdrew them [his ships] a bow-shot, the old man [Archimedes] constructed a kind of hexagonal mirror, and at an interval proportionate to the size of the mirror he set similar small mirrors with four edges, moved by links and by a form of hinge, and made it the centre of the sun’s beams–its noon-tide beam, whether in summer or in mid-winter. Afterwards, when the beams were reflected in the mirror, a fearful kindling of fire was raised in the ships, and at the distance of a bow-shot he turned them into ashes. In this way did the old man prevail over Marcellus with his weapons.

    Sakkas conducted his experiment on 6/11/1973 under cloudy weather in the Palaskas training center. He used 70 bronze plated glass mirrors 1.70 by 0.70 m in concave form. The small boat was 55 meters out at sea, took flame in under 1 second and completely burned in under 3 minutes

  3. The first series of attempts to recreate Archimedes’ mirror weapon was undertaken by Count Buffon in 1747.
    After Sakkas’ experiment, the most recent recreations occurred in 2004 (by the MythBusters TV crew, FAIL) and in 2005 (by MIT, Success!)
    Read about this ancient precursor of DARPA’s heat-ray technology in “Greek Fire, Poison Arrows & Scorpion Bombs: Biological and Chemical Warfare in the Ancient World” (Overlook, 2009)

  4. Wait wait wait; this is all going too fast.

    The experiments (I know of four of them, including the ones mentioned above), all point in the same direction: the principle is correct. This does not mean, however, that the Byzantine sources are confirmed. Tzetzes describes a comparatively small instrument that can reach “ships a bow-shot off”. This has not been confirmed. Sakkas needed 70 concave mirrors -not the straight mirrors mentioned by Anthemius, our best source- and needed several hours to direct them; he could only hit at a short distance. He would have needed 280 concave mirrors to strike at 110 meters, and more than a thousand to hit at one stade. This was also the conclusion of the MythBusters: possible, but impractical.

    Proving that the system might work is one thing; concluding that it did work is something else. Then you’re introducing, between argument and conclusion, introducing an additional element. This is the logical fallacy that is known as a secundum quid.

    The opposite logical fallacy is present in Anonymous’ comparison that “the fact that Pausanias description of the sinking of Helice also dates 5 centuries after the event does not reduce its historicity”. At issue is not just that our sources are younger; at issue is that our sources are younger and that we have old sources. In his comparison, Anonymous prefers to eliminate a qualification.

  5. Sakkas did NOT use concave mirrors. He used straight segments in concave configuration. Lazos spends two chapters in his book (one of them actually guest-written by Sakkas himself) arguing and describing using ancient sources that Archimedes DID know the concave configuration in concentrating light and that he used mirror segments in such a configuration. In his 1973 experiments (he did 4 demonstrations with planks painted with tar before burning the replica, in one of the experiments he burned the planks from a distance of 130 meters) he used seamen (a.k.a. drafted soldiers) to move the mirror segments. He did not need several hours to move them, after they had originally been trained to work in concert, they needed several MINUTES to steer the segements and could do minor corrections if the ship moved. In one second smoke came out and the replica (actually a big fishing boat with a sail and painted with tar outside, as ships were in antiquity) burned in under 3 minutes at a distance of 55 meters despite cloudy November weather. Unfortunately Sakkas never properly published his experiments, if we take out the newspaper reports and the preliminary report of the experiment in the Bulletin of the Technical Chamber of Greece, Lazos’ book is the closest thing he has to publication, and it is in (modern) Greek.

    I think I was misunderstood. Our early sources on the siege of Syracuse do not describe the event per se (like for example the 6 detailed eyewitness contemporary sources we have of the Avar-Persian siege of Constantinople) but as part of another narrative. None of the three are close to it chronologically, neither Plutarch (who wrote the life of Marcellus, not of Archimedes) nor Polybius nor Titus Livius. I again point you to Lazos’ book where he gives the arguements and does a bibliographic survey among modern historians showing which accept the historicity of the event and which do not. Helice is a valid arguement because the contemporary and superior source Xenophon does NOT mention its destruction from the earthquake but only Pausanias does who was many centuries later. Our sources are younger (Xenophon AND Diodorus Siculus), our sources are superior yet our LATE source Pausanias mentions it and is valid. Why shouldn’t the same thing happen with the burning mirrors?

    And oh, I am not very anonymous. I am always the same guy, ikokki, MSc in Agricultural Engineering from the AUA, MS SILAT in GIS and Remote Sensing from the grandes écoles AGROPARISTECH and Montpellier SUPAGRO. Nowadays, with the internet, one needs to guard his privacy …

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