Archimedes Mirror

According to legend, Archimedes, famous mathematician and philosopher developed a large mirror that could set fire to Roman ships from several hundred yards away. The stories date back to the Twelfth Century.

BOOK OF HISTORIES
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 center 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.

What do you think? Fact or Fiction?

www.mcs.drexel.edu...
www.math.unifi.it...

A google search shows many many hits to .edu sites. All that I looked at say that they think it is fact.

like this one where they replicated as (best possible) this with a succesfull experiment.

ARCHIMEDES: CRANES, CATAPULTS, MIRRORS

Archimedes played a major part in defending his natal city of Syracuse against a protracted Roman siege, as the designer of a host of weapons and machines to repulse the attackers. These fall into three main categories: a) cranes (or 'claws') that lifted enemy ships out of the water and dashed them against the rocks, b) catapults of every size and description that hurled bolts and stones varying distances, and c) the mirrors that focused sunlight on the ships and set them alight. This latter invention has become legendary, and much has been written about whether such a thing could in fact have been possible in the time of Archimedes. Most experts, and particularly foreign experts, were persuaded that the construction of such a system was a myth, despite the weight of literary evidence supporting the story, until engineer Ioannis Sakkas succeeded in demonstrating that it was indeed possible. Sakkas used 70 copper-plated glass lenses, with diameters ranging from 1.70 to 0.70 metres, and his experiment was carried out at the Palaska Training Centre on the island of Salamina on November 6, 1973. Sakkas placed his 70 lenses in a circle, and succeeded in focusing the sun's rays on a small boat, built in the same way as Roman craft and equipped with the same sort of materials, lying 55 metres away. In less than three minutes the boat was ablaze. Sakkas' experiment was reported around the world, and caused quite a stir. Three previous tests had also produced satisfactory results, and together they confirmed that Archimedes did indeed set fire to Roman ships. While we do not know the full effect of this conflagration, the psychological impact on the enemy must have been terrible. That, of course, is why his feat acquired the status of a legend and is still talked about to this day.

[edit on 1-1-2005 by makeitso]

Interesting. I remember as a kid learning that a mirror could be a very dangerous thing when reflecting sunlight into one's eyes. Perhaps Archimedes knew he could start a fire, or perhaps he hoped to blind the crew.

i know you can do it to ants and other small creatures with a magnefine glass, but i don't think its possible with a mirror. it seems more fairytale-like to me. the mirror would have to be prety big, and for the beam of light to still be that powerfull to set light to the boat, from that distance, i just think is impossible. with the magnefine glass you have to make the sun go through it so it makes a small dot, which concentrates it's energy. when you just reflect the light with a mirror the reflection wouldn't be concentrated, nor could it be reflected on to the boat to set it alight. the only good thing from the mirror reflection would be if it blind the guy who was sailing and he crashed in to the shore.

They tried to make this thing on Myth Busters and they couldnt even get it to come close to setting anything on fire. They made a 400 sq ft mirror using 300 individual mirrors arranged in a circular configuration, with all of the mirrors focused on the same point at a 60 ft distance. Apparently, mirrors can put out 30kW/sq ft, which means that their mirror could theoretically put out about 600 degrees of heat.

They managed about 200 degrees far from setting anything ablaze.The crew raised some additional sheets of reflective material, but was only able to get the temperature up to 280 degrees. One of the guys even stood in front of the beam for awhile not much of a weapon.

I would have to question the usefulness of this thing even if it could be made to set things on fire. I dont know how easy it would be to move a mirror this big to aim it. Also you would be trying to hit a moving target which makes it even harder even just the ship rocking up and down in the water would make it harder to focus the beam, on one spot.

Then you have the simple fact that you could just wait until night time or a cloudy day to attack.


[edit on 1-1-2005 by ShadowXIX]

Well I doubt the Myth busters can build a death ray in a day.

Its possible that it could have been true. But so much information has been lost that it's near impossible to recreate. Like the Wright Flier or Greek Fire.

It's possible that this experiment would work centuries ago, when the sun was brighter. In the last 30 years alone, we've lost ten percent of the radiation that filters through the aptmosphere. I bet you could have set wooden ships on fire with a sun reflector that had a high radiation sun to work with. The undustrial revolution might have made it impossible for us to set big things on fire from a distance with mirrors. Shucks. Nifty story though, that wacky Archimedes, I tell you..

Originally posted by Vegemite
Well I doubt the Myth busters can build a death ray in a day.

Myth Busters aint Junk Yard Wars they dont have to build the thing in a day. They really did a good job on this myth I was impressed with the mirror they made. Sometimes there methods are questionable but this was one of there better jobs.

But really if Archimedes had some type of solar weapon it didnt do him much good because Archimedes was killed in the sack of the city following the siege.

what about this for possible construction

1
use (perhaps multiple) thick glass plates (like a magnifying glass) to concentrating the light

2
project concentrated light onto mirror

3
position mirror to reflect beam onto target

will this combo work? any ideas?

The difference between Myth Busters and archimedes is that Archimedes had a life time of intelligence and experience to build this thing, he was also a mathematical genius, far more intelligent than the Myth Busters crew.

I mean this is the guy that layed down basic logic and math for us, and even surpassed that. So I do not doubt that he did this, plus alot of things created in the ancient times was lost due to a giant fire. Putting all knowledge in one building, not one of our smarter ideas.

The greeks managed to build a computer, they can definetly build a giant mirror capable of setting fire. Also, the conditions at the time were very different, take that into account.

Shattered OUT...

Dont get me wrong Archimedes was a very smart man , but these accounts of the mirrors come from the 12th century over a 1000 years after the fact.

by John Zonaras (circa twelfth century AD)

" At last in an incredible manner he [Archimedes] burned up the whole Roman fleet. "

Dont you think the Romans would have gave up after such a weapon was used wouldnt there be more older accounts of such a weapon? Yet the Romans still sacked the city and nobody writes the story down for over 1000 years. Perhaps he had plans for some type of solar weapon but i doubt anything was ever put into use.

Originally posted by ShadowXIX
Dont get me wrong Archimedes was a very smart man , but these accounts of the mirrors come from the 12th century over a 1000 years after the fact.

by John Zonaras (circa twelfth century AD)

" At last in an incredible manner he [Archimedes] burned up the whole Roman fleet. "

Dont you think the Romans would have gave up after such a weapon was used wouldnt there be more older accounts of such a weapon? Yet the Romans still sacked the city and nobody writes the story down for over 1000 years. Perhaps he had plans for some type of solar weapon but i doubt anything was ever put into use.

You are true, the older historicians like Polybius or Livius are writing nothing about mirrors, just about catapults, huge robotic hands, etc.

It is true but he didn't use a mirror, because mirrors dont reflect enough UV to start a fire, instead he used the polished bronze shields from the soldiers.

Originally posted by SmokeyTheBear
It is true but he didn't use a mirror, because mirrors dont reflect enough UV to start a fire, instead he used the polished bronze shields from the soldiers.

Creating a mirror effect correct?

Yea, thank you for proving yourself wrong.

Shattered OUT...

Maybe the mirror had a concave surface to it so the light was reflected in a focused beam. I think it is possible this way with enough large mirrors. I wouldnt say there is no possability for this device. Especially considering the builder of it. Archimedes was responsible for the Infinite screw, and many other useful devices. If someone could have devised this device, it would have been him... or Devinci

Creating a mirror effect correct? Yea, thank you for proving yourself wrong. Shattered OUT...

Shattered, it is good that we all get to express our point of view.
Be that as it may, since the point of this site is to Deny Ignorance, and if you really think that bronze was and is not used for mirrors, please see:

Google Search Bronze Mirrors

makeitso

What about a seiries of concave mirrors with a single lage one that you could angle to hit a target? The smaller mirrors would focus the light into the larger one. You could then hit a target in almost any direction.

[edit on 2-1-2005 by replicators]

I forgot who in the post said this, but some one mentioned something about the suns radiation, i just made me think that if the atmosphere was pure and way cleaner than it is now, couple with the possiblity that more radiation was being generated by the sun/ or able to enter our atmosphere, it might have worked.

Yeah, I said that. And here's another link, maybe Archimedes used a design similar to the Fresnel lens

en.wikipedia.org...

You can take one of those magnifying mirrors that come with larger make-up compacts and very quickly set fire to a piece of paper, and you can cook with a halogen headlight housing pointed at the sun, so I don't see how you guys can call on mythbusters to debunk a really basic principle of focused and reflected sunlight. I really have no sympathy for folks that assume ancient automatically means ignorant.