Picked up one of many books I have on the go to try to fall asleep (this one usually works - "One Good Turn - A Natural History of the Screwdriver and the Screw" by Witold Rybczynski. In reference to Archimedes, a truley brilliant dude, designed alot of things. Rybczinski writes (p137) "His most renowned weapon was a miroor that beamed the sun's rays and set the attackers' ship on fire. To prove the practicality of what had long been considered merely a colorful legend, in 1973, a Greek engineer named Ioannis Sakas built a working version of the ancient ray gun.11 He used seventy bronze-coated mirrors, which he aimed at a tarred plywood cutout of a ship. At a distance of 165 feet, approximating the "bow-shot" that is mentioned in the classical text, it took only a few minutes for fire to break out." Footnote 11. New York Times, November 11, 1973.
Was this myth busted? I think it was but can't remember. I would love to know if anyone has done the research on this, and could or has found the info on the experiment conducted in '73.
"a few minutes" is way too long to be useful as a weapon. In that amount of time, the Romans would have hauled into shore, destroyed any mirrors and generally handed Archimedes and Syracuse it's @ss without even breaking a sweat. They certainly wouldn't have obliged the defenders by dropping anchor and remaining in one place all that time.
It is telling that Sakas' demonstration seems to have vanished. It's utter impracticality is certainly the reason.
of course in his experiment he would find a way to make it work... in an irrational setting
reflected light is low in power (the light is dimmer and bronze absorbs heat), and is diverged at distance
Can't focus well manually at large number, let alone the fact that focal point is difficult to estimiate, decide and report to everyone in a short time.
Reflected light = 1/10 reflected heat = 1/100 reflected, not diverged heat at focal length = 1/500 After manual error = 1/1000
After sea breeze taking out heat, efficiency = 1/2000
takes 2000 shields' reflection to get 1 shield area's heat at focus
I found a magnifier (low or no loss in heat from sun) still takes 2000 into 1 to burn a piece of wood (coated with flammable paint) at a few inches
so you'll need 2000*2000 bronze shields to make it works, or 4 million shields...
and it is not difficult to notice the action and find something to stop, eg dampening the light spot area, reflect it back, sailing zig zag, ...
a burning catapult stone is cheaper and easier
ps.
if that was a hot day, the air above sea would change in density, making light rays deflected and more difficult to focus.
Solar energy heliostats routinely generate temperatures in excess of 2000 degrees, which is plenty hot to burn wooden ships (or most anything else, for that matter).
When people use numbers, it really isn't fair unless you really know how the actual equations work. Heat isn't the square of light, for instance, and the reflectivity of polished bronze isn't 1/10th, it's closer to .85.
Also, just because the earlier referenced test took "a few minutes" to set a test rig ablaze doesn't mean that it would've taken the Syracuse army that long.
One thing common to every test of the "myth" is that the resources of the people doing the test are tiny compared to those available to Archimedes.
It would be like trying to say that the moon shot really didn't happen because you can't replicate it on a shoestring budget. However Archimedes did it (or didn't do it), they were facing the Roman army and had two options, come up with something that'd work, or lose the battle and become Roman slaves. Thus motivated, I'd have expected them to try anything. With Archimedes there, I'd expect him to come up with something clever. Maybe this wasn't it, maybe it never occurred to him to polish bronze shields to set Roman boats on fire, but the concept itself is viable.
After all, we're talking about doing essentially the same thing when we're using lasers to shoot down missiles, right?
This message has been edited. Last edited by: carterelliott,
I can't believe all the "Contestants" went for direct focus arrays.
I would have used a linier array focused on a central tower mirror on top of the "castle" wall. The array only needs to be focused once on the tower, then the tower mirror does the final focusing and tracking of the target.
The array can be protected from attack behind the fortification and need not have line of sign to the target ships.
[quote]which he aimed at a tarred plywood cutout of a ship.[/quote]
Lest I checked, Triremes weren't made of plywood. Triremes were of solid Timber Construction.
[quote]Solar energy heliostats routinely generate temperatures in excess of 2000 degrees, which is plenty hot to burn wooden ships (or most anything else, for that matter).[quote]
Perhaps you are thinking of this?: http://en.wikipedia.org/wiki/Solar_Two
The Commercial Power plant, Solar Tres, is being built with 2,493 93m^2 reflecting mirrors on heliostats.
That is: 231,849 m^2 2,495,601.87 ft^2 57.29 acres of reflective surface area.
Yes, acheving high temps with solar reflectors is POSSIBLE, but utterly impractical and just plain silly to attmept as a weapon. The manpower and material that would be required to make this weapon work would be 10 times more effective utilized conventionally.
[quote]was magnifying technology available during Archimedes time??[/quote]
Any concave mirror will tend to focus light and have a magnifying effect.
Somebody mentioned "lenses", and big lenses are impractical, even today. They have to be thicker in the middle to have a real focal length, and when you make them big, they get very heavy. For large apertures, you really need a mirror.
Something kinda off-topic here that occurred to me the other day is that Archimedes really wasn't known for his optical innovations (to my knowledge), he was noted for understanding buoyancy. Since it wasn't a historical fact that he defended against the Roman fleet using the sun's energy, maybe he did it a different way.
[quote]Something kinda off-topic here that occurred to me the other day is that Archimedes really wasn't known for his optical innovations (to my knowledge), he was noted for understanding buoyancy. Since it wasn't a historical fact that he defended against the Roman fleet using the sun's energy, maybe he did it a different way.[/quote]
Archimedes was really into Geometry and mechanics. The earlier accounts of the battle of Syracuse speak of large lever-driven weapons that lifted ships out of the water as they approached the walls. He was also known for the development of missile weapons such as Tortion Ballistae.
The lever-weapons supposedly used by Archimedes at the battle of Syracuse as described by Plutarch seem a bit...mythical...to me.
Perhaps we nee a "Did Archimedes REALLY toss Triremes around like bathtub toys at the battle of Syracuse?" Episode.
I think that, like nearly all Myths, the engineering feats of Arhcimedes durring the battle were exagerated and expanded with each re-telling of the story. The "Death Ray" is just another embellishment added by some later so-called "historian".
This message has been edited. Last edited by: imminentstorm,
I think the idea of the death ray is definately a possibility. Even though they need to focus on an object, which would make them impractical for lighting ships on fire, I would imagine that would have been taken into consideration. It struck me one day that if they used some sort of container that was floating in the water and possibly anchored down, they could fill the containers with flammable material and place it in a location they know the mirrors can focus to.
Since the test wasn't done on a moving target, I don't see how it's valid. A fleet of Roman ships is not just going to stand still while Archimedes dials in a death ray. The weapon would be impractical if it's not impossible. It seems like this one's busted. It's about as likely as him unleashing sharks with laser beams no their heads on the Romans and demanding one billion dolars *puts finger to corner of mouth and laughs maniacally*.
Most of the problem with using the sun is it MOVES. Has the MB crew seen a survival mirror from WWII (maybe later also) used to flash light on a distant rescuer? Flat, or concave, highly polished shields need only a small hole through a polished back surface to be accurately aimed at targets miles away. You then only need to agree on where to aim for everyone to hit the same spot. This was not beyond the technology of the time. Bigger mirrors with one person each would give a vastly different result.
Anachronistic. You will search the dig records in vain for mirrors with holes in them. Besides, ancient glass mirrors were only about the size of your hand.
The concept of using sighting/signaling mirrors was only developed in the 1800s---so George Washington couls not have done it, much less Archimedes.
You talking about modern signaling mirrors? They come standard in survival-adrift packs that can be bought at marinas. They use to be in Boy Scout cataloges and mabe still are.
for all of you who insist the romans wouldn't oblige the syracusians by sitting still need to read up on the siege of syracuse(212-211 BCE) and also siege techniques of the period in general.
Roman artillery ships were at anchor in the harbor. Roman ladder barges that made it to the walls were also stationary.
#2 No seperate people/groups with mirrors. A single device was presented in the byzantine myths.
quote:
One thing common to every test of the "myth" is that the resources of the people doing the test are tiny compared to those available to Archimedes.
Well said. Archimedes was the technical advisor to the defense minister of syracuse and everyone concerned had years and months to augment and improve the already impressive defenses. The ship-shaker cradles and swing-arm devices are proof of that.
for all of you who insist the romans wouldn't oblige the syracusians by sitting still need to read up on the siege of syracuse(212-211 BCE) and also siege techniques of the period in general.
Do you think we could get some actual, you know, evidence that anything of the kind took place? Contemporary accounts of the battle make no mention at all of any "death ray"; they don't even mention burning ships, a detail that was added centuries later, with the "death ray" being tacked on to medieval accounts nearly a thousand years after the fact.
That, added to the sheer ridiculousness of such a "weapon," busts this wide open. It really wasn't necessary to try a half-dozen times to show the utter futility and foolishness of the idea.
Contemporary accounts? Where are they? I would love to read them.
Of course the device is foolish. Of course a weapon like that has way too many limitations to be practical. But so were the ship-shaking cradles and swing-arms, yet they were made and deployed.
So many reasons people are giving for the thing NOT to have been real are just not based on the facts and are just as presumptious as some of the reasons given for being in favour of the confounded thing.
Pull your fork out of it if you wish. If it's done for you then why even click on this topic to begin with?
