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Archimedes Death Ray
Werner Heuser writes "Ancient Greek and Roman historians recorded that during the siege of Syracuse in 212 BC, Archimedes (a notably smart person) constructed a burning glass to set the Roman warships, anchored within bow and arrow range, afire. The story has been much debated and oft dismissed as myth ... Intrigued by the idea and an intuitive belief that it could work, MIT's 2.009ers decided to apply the early product development 'sketch or soft modeling' process to the problem."
For the unitiated, 2.009 at MIT is a class in course 2 (mechanical engineering), called Product Engineering Processes.
... and the server is a smoking husk before the first comment is posted.
Help poke pirates in the eyepatch, arr.
The server seems really slow right now, try this.
And Mythbusters is LAW!
The Tech Terminal
Not to argue that the mythbusters are always right, but they've disproved this in one of thier episodes. They did some pretty good convincing after building a trireme and using a few hundred mirrors and only reaching a couple of hundred degrees (F).
h busters.html
Mythbusters: http://dsc.discovery.com/fansites/mythbusters/myt
IT BURRRRRNS! The same Archimedes whose last words were "Do not disturb my circles!" at Syracuse. The Wikipedia article links to the same story at MIT. http://en.wikipedia.org/wiki/Archimedes Quite the inventor!
That's an Archimedes Death Ray, now banned from all commercial airline flights. Lame.
This sort of demonstration has been done before. I remember reading an article in Time magazine in the 1960's or 70's that reported on one such earlier experiment. Many men held polished flat "shields" in the sun at the right angle, and confirmed that they could cause charring in a simulated boat target.
I personally thought that they didn't do a very good job at testing it and they could have definitely gotten it to work if they did a better job setting up the mirrors. (of course they like to claim they "busted" something even when it was inconclusive or mostly true)
Flash ignition!
In an instant there is a large, open flame. The volatiles liberated from the wood ignite at roughly 1100 F.
Open, sustaining flame occurred less than 10 minutes after the sun was in a clear patch of sky!
You can also clearly see that there are still 3 mirrors not aimed correctly.
Now that Mythbusters is wrong, are there other myths that could be true?
if the ships were within arrow range... wouldn't a flaming arrow have done the job just as well... why the over engineering?
Not exactly the same concept, but the Solar Death Ray always reminded me of this.
How's my typing? Call 1-800-eta-shut
No wonder why the webpage says:
8 15d479865f65c52/index.html
"Click on image thumbnails to see a larger images. Video clips will be online next week"...
Why next week?
Can't we just take down the entire MIT web server! =P
So, those poor students in mid-session won't be able
to access to their course material and similar! =)
That's nice a new excuse just came out!
"Sir, I couldn't do my assignment, because the MIT web server was slashdotted,
so I couldn't access the course material, can I get an extension.... PLEASE!!!!"
So, next time, you guys have a hard deadline assignment,
please just post an article on slashdot and there you go.
For everyone else, please use the Mirror...
http://www.mirrordot.org/stories/90e7777b89ad9e53
For what it's worth, the MIT folks said they couldn't unequivocally rule it out. They didn't say it happened. One of the main points on Mythbusters was that it seemed like it might work, but the fleet would have had to remain essentially motionless for the wood to get hot enough for ignition. The MIT folks did nothing to answer that as they the mirrors and the "ship" were motionless until ignition.
If Nalgene water bottles are outlawed, only outlaws will have Nalgene water bottles.
as tin foil hadn't been invented yet, his enemies would have had no viable defense against this weapon. Devastating!
The Slashdot death ray doesn't even use mirrors!
Solar Death Ray
Looks like the renewable energy people are in on it, too
I also remember seeing one in my chemistry book last year... it was in france or somewhere (theoretically temperatures could get high enough to ignite something with a low flashpoint like wood or paper). The mythbusters' argument was that copper wasn't shiny enough and that even with mirrors, the soldiers wouldn't have enough precision to focus on a point for long enough.
-TX297
The mythbusters set up a more realisitc scenario to test with, they had a real wooden boat that was harder to combust due to the protective resin that was coating the boat, their test was more true to the original myth then what the MIT trial was I think.
MIT's boat wasn't even in the water, they were just pointing mirrors at dry wood.
A boat would have also been damp which would have also made it harder to combust.
Yes, but IIRC the show also pointed out that an earlier generation of mythbusters had demonstated it is possible to set a wooden boat on fire using soldiers holding large mirrors. Each soldier directs an individual mirror onto the boat, use enough mirrors and it will start smoking.
I don't belive the ancient greeks had the technology to make a glass lense large enough to fry a boat, let alone focus on a moving target. However it is certainly possible using multiple mirrors, even the crude ones made from polished metal like Archimedies would have had access to.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
I dont think the resin would be all that protective. It was pitch - a long chained hydrocarbon that would burn like buggery once it was hot enough to vaporise.
in 212 BC, Archimedes (a notably smart person) constructed a burning glass to set the Roman warships, anchored within bow and arrow range, afire.
If the enemy ships were anchored within bow and arrow range, I suspect that while Archimedes was fiddling with his mirrors, a few archers dipped their arrows in pitch and fired them at the fleet. Eventually, when Archimedes finished aiming his master weapon he was overjoyed to discover the fleet in flames. Archimedes reported his success to the king, and went down in history as the oldest recorded example of a horribly over-engineered solution to a simple problem.
This, of course, is where the "Gods From Space" crowd chimes in. Works on TV, but in real life, there's a much more satisfying answer: people are damned fucking clever.
I'll swear there was a MST3K featuring a truly awful film of which the premise was Archimedes had built a death ray. I can't remember the precise name, but god it was awful...
Igniting sails, or burning/blinding people is much easier than setting fire to wood (especially a hull that could be wet). I've always thought that the victory was due to the psychological effects of the weapon on morale more than the outright destruction of vessels.
mythebusters clearly cut part of the card throwing episode. Measurements were taken for metal cards, you can see it in a tivo slomo. It was wither cut for time, or the fact that it was found that the metal cards would cause major damage.
I've never heard a good explanation about who built it, only that it was known that there were repairs done (or deduced from the sections of gears that had been replaced with different material) and that it was made around 50 BC - something like that, I think my dates are wrong. It would be interesting to have someone do a spectral analysis of the metals used (unless being submerged for that long in salt water drastically changed trace element properties in every single bit of metal) to trace back to the region of origin, where the metals were mined. I think I read about doing metalurgical traces by geographic reigon once, where they compared samples from ancient mines to trace amounts in artifacts, and could narrow down where it came from. Back to the whole point of my tirade, it would be interesting to find out, for instance, that the metals used in this device came from india, or china, etc. Might not tell us "who built it" but it might be valuable nonetheless.
Yes, Archimedes was a very smart cookie, but he was surrounded by other smart cookies, who were also geting up to interesting things. IMO, ancient Greece was pretty much as technologicly advanced as 15th century Europe. Why we ended up having the industrial revolution, and the Greeks did not, becomes a very interesting question.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
A mirror can also prevent the server from burning up.
Marvin knew: "Think of a number, any number..."
"Carbon in the wood is burning, which means the surface is at least 750 degrees F. "
So what's that in units that the rest of the world uses?
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PGP Key ID 0xCB8FF658
I remember a Mythbuster episode where Adam & Jamie try to reproduce this myth/story. They were not able to set a boat hull on fire (they built a replica-piece of boat hull from that age). Stronger still they barely managed to get the temperature higher up... iirc it was only a few degrees higher in the focused center of the beam.
The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.
This was built in mini-form on a show called screensavers. It use to aire on G4 a year or so ago before it go turned into Attack of the Show. They proved that it worked by placing an object infront of the mirror (about 2 feet away) and just about instantly set it on fire.
The problem with mythbusters, and they do this often, is they only did one test to see if it would work in one way. They only aligned the mirrors in one direction, every single one of them at the same degree, meaning that the light that hit the center mirrors wouldnt reflect on the same spot the top mirrors did. If you watch the show they did, you can clearly see the reflection of the mirrors all across the 'boat' from 3 to 6 feet, not on a single point. That means that the mirrors didnt concentrate the light energy in one spot and were only able to get the spot to around 200 degree's.
Guess what? It doesn't really matter, because despite the intuitive belief that the 2009ers profess that it would have worked, the evidence (Rome sacked Syracuse and Archimedes was killed -- some say inadvertently) demonstrates that if it did work, it didn't work well enough.
Dude, I think I can see my house from here.
It's also possible that the ships were a lot more flammable than the mockups used in the tests, if they were caulked with pitch (it is not known if they were or not).
I saw something on TV about another scientist at the time. This guy developed a device that used steam to cause a ball to spin. The water was boiled in the base, travelled up the support rods, into the ball, and out two ejection ports on the outside of the ball. The mockup they showed spun really fast. If this guy had thought of it as more than a toy, he would have started an industrial revolution.
They run these unscientific experiments (most involving explosions or decaying corpses) and then "conclusively bust" myths. Some experiments are fun and interesting, but most don't deserve the hard conclusions they assign.
It's really annoying when people take accept their "proofs" as proofs.
Yep, but as ohters have said, the greeks used slave labour for their construction/manufacturing and therefore had little incitement to invent other things than warmachines (greek fire, imagine a giant roman candle) and toys (as in this example with 'agitated air' as he called it as far as i remember).
Yours Yazeran
Plan: To go to Mars one day with a hammer.
The other answer to my post from the AC above probably nailed it. "Why build a factory when you can have slaves do it?" The class of Greeks that had the time to dabble with steam engines had no incentive to build labour saving devices.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
Not really all that interesting of a story in my opinion.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
Actually I think that if they really studied history they would note that Greek Fire was probably invented in 673 AD (at least according to your wikipedia article), a number of years after Archimedes died. You might as well say this was an early incarnation of napalm.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
It's in Spanish, but it does have a photograph of about 40 of the 70 man-sized mirrors they used. He managed to ignite a tarred wooden boat in about 3 minutes.
I am now seeing "Forbidden" when trying to access the original MIT web page, however Google claims there is mention of the Sakkis experiment on this one (also forbidden).
Heron of Alexandria invented a kind of steam engine. He was mathematician, physicist, and an engineer who lived between 10 and 70 AD.
This is before bow 'n' arrows, back in a time when lasers were the weapon of choice.
I remember when legal used to mean lawful, now it means some kind of loophole. - Leo Kessler
Since the Greeks had gears and ropes, it would have been possible to build a mechanism whereby one person could rotate many mirrors. I'm not saying it would have been easy, or even that it was done this way, only that they had all of the required technology to do it.
A second possibility would have been similar to the sighting mechanism used very successfully by the Dambusters in their attacks in World War II on German dams. They needed to know when they were at a certain height above the water, level, and at a certain distance from the dams. They achieved this by angling the searchlights to cross over at the right height and strike the dam at the right distance. To know if they were level, they used pieces of wood at different distances, which would line up when the aircraft was level.
To line the mirrors up with the ship, you'd need to know when the light from the sun would strike the ship at the right height. Angle of incidence equals angle of reflection, so as the sun moves through the sky, you'd need to shift the mirrors both horizontally and vertically to keep the light on the right spot.
If you had a hole in the mirror and stood behind it, you could swivel the mirror to face the ship. Since the ship would be at water level and the mirror would probably have been much higher, the mirror would have to have pointed at the tallest mast. It would be the only thing visible. To ensure all mirrors pointed the right way, each mirror would need behind it a stick that needed to line up with the mast, but set at an angle such that each mirror would line up differently along a crude parabolic curve. Shouldn't have been hard, with the Greek knowledge of geometry, which they were exceptionally good at.
If the action was brief enough and at the right time of day and at a predictable distance, the vertical angle would be unimportant. If it had to be ready for ANY time of day OR at ANY distance, then you'd need to have the poles on which the mirrors were attached themselves movable.
If you mounted the pole on one end of a see-saw, then added weights to the other end, you would be able to adjust the vertical angle of the mirror to whatever was required. The line of the see-saw would be parallel to the normal of the mirror. You can tilt the mirror such that the reflected light will intersect the ship at the same point that the line along the see-saw intersects the ship. This would guarantee all mirrors get identical vertical alignment.
We now have a guaranteed way of aligning a great many mirrors onto an identical point on a ship at any distance at any time of day, using nothing more than geometry, alignments and pivots. Again, this is NOT to say that this is how it was done - we don't know HOW it was done, or even IF it was done. What this is saying is that the arguments against have largely been based on sophistication, but that the required level of sophistication was certainly achievable had anyone wanted to achieve it.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Wow, boat nerdfight!
Read your link. Greek fire was invented in 673 AD.
The ancient Greeks were not stupid. When they wanted unusual materials, they just ordered them on eBay.
Something like only needs to be used once to be effective. After that, the mere idea that it exists is a deterrent. Two other examples of this working:
1) The ancient Israelites carried a large gilded box called the Ark of the Covenant in front of them into battle. They believed it could summon up the wrath of God on their enemies. Their enemies were not 100% sure that the Israelites weren't right. There is no evidence that the Ark ever actually did summon up the wrath of God, but boths sides beleived it and the Israelites beat enemies who had superior numbers on a number of occasions.
2) How many atomic bombs were actually ever used? Two. But the mere thought that a country has nuclear weapons gives them a bargaining position. And the the fact that the wrong country even MIGHT be trying to obtain them is reason to go to war.
In the ancient world, this "death ray" would have struck fear in the enemies hearts and minds, despite the fact that it might have serious limitations, or may not even work at all except in controlled situations. And one or two prominant demonstrations of such a weapon would go a long way toward keeping this fear going.
One common criticism of this theory is that coordination and aiming would be too difficult to be practicable.
It might be possible to engineer a simple method to coordinate the aiming of many mirrors. First assume that your soldiers are standing in a fixed formation and distance relative to their target. (i.e. a straight line)
Each soldier is holding a mirror which is joined at the base to a board, at an angle of 90 degrees. Put a tiny hole in the mirror, so that a point of light falls on the board to which the mirror is attached. Each soldier now has an indicator of the orientation of the mirror. On each board, an ancient geometer has inscribed a grid. (intersecting parabolic arcs, in the case of a straight line of soldiers) If each grid is drawn appropriately (different for each board), then a commander may call out a row and column and each soldier orients their mirror so that the pinpoint of light falls on the appropriate point.
Implemented as simply as I describe, I doubt this arrangement would be suitably precise, but with a larger (possibly two-person) apparatus and provisions for increased stability, it might be possible to quickly focus the hundreds mirrors required to achieve combustion. The only skill required of the solders would be the ability to stand in a straight line and know the alphabet.
Don't forget Archimedes acquired a reputation in his lifetime that has lasted more than two thousand years. That is, he was not only considered the smartest man in his generation, but one of the smartest men ever to live for another hundred lifetimes of men, all over the Western world. He was very probably the ancient world's equivalent of Newton, Einstein and Fermi all rolled into one.
Further, given that he was at the time of his supposed feat a powerful figure in Syracuse, and the fact that the fate of a conquered ancient city was dire -- the city leaders would be paraded and killed, and everyone else sold into slavery -- Archimedes probably had access to all the material wealth of the city, and as much willing -- nay eager -- manpower as he could wish.
Given those facts I would hesitate to scoff at the myth on the basis of what can be achieved, or not, by a mere dozen modern men, of average intelligence* and creativity, working with trivial amounts of money, and not nearly as motivated as men facing enslavement, an ugly death, or in many cases both.
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* Yes, I know the MIT students are no doubt above average in intelligence. But the odds that their number includes someone so clever and inventive that his name and accomplishments will still be common knowledge twenty centuries from now seems remote, to say the least.
That is, if you use mirrors that are mirrored on both sides, and have a hole in the middle. See, then all you have to do is hold the mirror up to the sun in such a way that the mirror casts a shadow on your own body. Then, looking at your reflection in the back of the mirror, simply line up the the reflected hole in the shadow with the hole in the actual mirror, while you can see the target through the hole.
The mirror is then at the proper angle. Keep using the hole to aim, and keep the shadow lined up, and you can easily track the target.
I saw a diagram of the geometry on-line somewhere, but I can't seem to find it now. It would make it a little easier to understand, if you can't parse my description.
Two points I haven't seen anybody raise.
First, the ship would be constantly moving because of waves. This makes it a tad harder to heat up one spot to igniting and means that the spot would have to be fairly large for this to work. Bigger spot means that we need more mirror surface to heat it enough to ignite.
Second, solid mirror would have fixed focal distance. That means such weapon would have fairly limited range.
remember, this was supposedly used against ships trying to either get near sea walls or drop off soldiers onto walls / quays / seafronts... it would have been fairly easy for archimedes to ensure that the roman ships had to pass through restricted spaces (sinking boats round the harbour, laying chains, dropping piles of boulders etc etc); it may even have been the case that there were only a few places where the roman ships could get close to land simply because of the layout of the place. in which case, you wouldn't need lots of people trying to aim lots of moving mirrors at moving targets- a few pre-aimed ones covering strategic spots could be used whenever a ship was in the right place. if the ships where disgorging soldiers, they'd have to keep still for several minutes at least.
if i was archimedes and trying to attack moving targets with a weapon that was best used on stationary targets, my first thought would be to hamper the targets' movement.
it's a basic principle of fortification and defense - ensure the enemy has to pass through or in front of a concentration of your best firepower to get to you. it's why castles have gatehouses, un-aligned entrances, and towers with arrow-slits covering the area immediately in front of the walls. you don't need to attack the enemy while they're a hundred yards away - they'll come right up to you. if they retreat out of range, it means you're winning.
Andam Hart Davis has a programme on the BBC at the moment and in it he created the experiment at a smaller scale. He used a round disc with a lot of small flat mirrors that could be tilted to focus a beam of light onto a boat. With in a few seconds smoke started coming out. It worked and was shown on tv recently.
You are ALL missing one very important fact. Back in Greek times, the earth was 1000x closer to the sun, and the sun was 100x hotter. So only one small mirror was needed, and a lot of Coppertone Suntan Lotion. Why do I have to teach you important scientific facts time after time after time?? You Earthmen are stupid, STUPID!! No wonder Xangargo will conquer you.
So i got to read it...
Looks like they calculated how much energy it would take, then upped that by a bit, then carefully aimed their mirrors to achieve the required flux. It worked. If they were able to get smoke from 129 self-aimed, 1ft. mirrors, get a few thousand soldiers on a hill, and see what they can do.
btw... the math on the power of the mirrors is wrong. if the mirrors are flat (and you can think of a curved mirror as many small flat ones), then the mirrors effectively apear to be another sun. from the targets point of view a mirror(or part of one) is either reflecting the sun or not. The total flux at any point comes from how big (angular) the total surface of all the reflecting mirrors apears to the target. That's why a small, close, shaped reflector (or lens) can burn things, and why it's harder to scale up.
-John Fenley
For one, they do *many* more experiments than they show on air. Check out their website for details - basically, for every one experiment that makes it to air, they did 5. In reference to this episode in particular, you can be sure they tried many different cell models with many different levels of gas. These guys have quite a large budget to work with, they aren't going to skimp out on one cell phone.
For two, in reference to this particular episode, they did bust the myth that a cell phone can cause an explosion *through normal useage*. What they ended up saying, is in all likelihood the reported explosions were not coming from cell phones, but were a result of static electricity buildup at the scene. This is entirely plauseable. In my last car, depnding on the clothes I was wearing, I would often get actual blue sparks coming from my fingers to the door handle if I touched the car in the wrong way while getting out of it.
An explosion from a spark caused by static is much more likely than anything caused by a cell phone. How could useing a cell phone or having it ring *possibly* be any ore dangerous than a car radio? The car radio operates simmilar electronics, and hell, old ones even have rotary contact-based resistors for the volumne, which would be an ample source of spark potential. Any cell phone whose batter is sparking is not going to work properly because the battery is not making proper contact with the battery, so your calls would be constantly dropping. No one would use it.
I can only assume you were misinformed or made the wrong assumption about the show. Perhaps you are missing out on what Mythbusters is about. It's this funny little thing called "entertainment".
It is not an "Educational" program. It's about 2 guys who used to do FX work for Hollywood using their skills with "getting close" to the right thing trying to see if they can replicate urban legends.
The funny thing is, you probably missed the episodes where they revisit old myths they worked on. If the show receives enough requests from the audience or they decide they didn't do something justice, they give it another go. They did the "chicken gun" myth a couple times because they kept doubting their setup. I didn't get to catch the final conclusion, but I would say that by the time they were done, they had tried everything available to them to see what would happen.
Other examples of where they've done things incredibly right include hanging a pig carcass from a hook on a pivot and shooting it with various guns to prove that no, taking a gunshot does not make you fly back and do cartwheels, and using a ballistics gel dummy (with a pig backbone to simulate the human one) to determine if you could be injured by a ceiling fan (even the high-powered ones didn't do much until they sharpened the blades).
Yes, most people who have shot guns would understand that Hollywood fakes it, but for the average Joe who just watches movies and TV, with no physics background, it was probably something neat to see.
Yes, they blow stuff up. They put a crash test dummy through hell. Yes, they keep fuck-ups on the film, because that makes the show more approachable to the target audience- it isn't a dry, we-just-provide-the-facts-ma'am-only-the-facts show. It is supposed to feel like you and you buddies could be right there with them. You know what, though? It's entertaining. And for a channel that brings us 5 variations on "hey, we're going to destroy a room in your house by letting a half-assed decorator come in and ruin your happiness", it's a damn good show.
Many of their conclusions are valid. They've shown that pissing on the "live" rail of a 3-rail train system will not shock you (urine stream is too fragmented by the time it hits the rail for electricity to travel), exactly how many bug bombs you would have to set off in a room with an ignition source before the gas was concentrated enough to explode, and that you cannot get sucked into the intake on one of those firefighting helicopters while wearing scuba gear, only to be dumped into the fire and die.
The experiments are just as bad. The biggest problem I have is that they seem to have no awareness of significance testing. Without an evaluation of the statistical significance of their results, they can't claim to have proved or disproved anything... A negative result ("busted") could simply mean that their sample size was too small.
I love the show, but it would never pass peer review :-)
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
http://www.imp.cnrs.fr/foursol/1000_en.shtml
Really, really, really smart people 2000 years ago were probibally really, really smarter than most people now. Additionally Archimedes was very familiar with the materials available. It is very possible that the best and brightest of today would fail because they couldn't believe that a technology of the day would have been able to make sufficiently reflective mirrors etc.
I saw a show on TLC last week (I have no idea what it was called... caught it channel surfing while it was already started) where they were building devices by following the drawings of Leonardo daVinci.
That was one of the most fascinating hour of TV I've ever seen.
Anyway, I caught it when they were about to try the giant crossbow, and they had strayed from the design to use modern techniques which they were reffering to as much more efficient and superior to what Leonardo had access to. And they could barely move the projectile.
Then someone on the team forced them to do it right, and the thing flew out.
I could tell that the modern way was weaker than the original just by looking at it. The only thing that the modern way had going for it was that it was easier to do.
The lesson is: Newer != Better.
Just because a lot was invented since doesn't mean that they couldn't do anything with what they had.
You can't take the sky from me...
I respect the fact that MIT has its own unique course numbering system, and curricula are referred to by numbers rather than by name. However, it does bug me that MIT folks expect their bizarre internal numbering to make sense to outsiders. If one didn't know better, one might even see it as some sort of bizarre exclusionary "in group" code. But I suspect that it's just cluelessness, combined with intense isolation.
Thanks for the breath of fresh air, Tum.
WWF (aka All Georgia Pro Wrestling) = entertainment
Penn & Teller's "Bullshit" = acerbic entertainment
Mythbusters = geeky entertainment
Nothing on any of these shows is any more true than anything you'd see in Archie Comic Books. It's supposed to be fun, people, not a freakin' belief system!
There is a technique for aiming the mirrors easily and quickly, provided that one person holds each mirror and the mirrors are reflective on both sides. Make a hole in the center of the mirror. Open only one eye. Position the mirror so that you see the target in the hole and the sun shines through the hole onto your face. Tilt the mirror so that the image of the spot of sun on your face is centered on the hole.
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I bet Archimedes could have easily got 1000-5000 soldiers. Or maybe even archers - who'd be good at this thing (decent eyesight, steady hands etc). Whether he was able to get enough flat bronze mirrors is another issue, but I won't be surprised if he was able to do that - Syracuse wasn't that poor.
It's not that difficult to aim the sun's reflection at a target. As some people have already mention, some methods would involve putting a hole in the flat bronze mirror and using the hole to aim.
I'm sure Archimedes would have figured out many other ways of doing it, possibly more practical given the circumstances. He definitely was smart enough.
So yeah, on a clear sunny day (not uncommon in that part of the world), if you see 1000 people each with a large flat bronze mirror reflecting sunlight to you, I think it'd be best to make a quick retreat and come on a cloudy day.
BTW, Archimedes also had other defenses against ships attacking the city walls by night.
I guess the persistence of the Romans worked in the end.
You were watching PBS... just giving credit where credit is due. It was excellent. I had to double check that I still didn't have cable or satellite.
See the Pictures of the Flood of '08