Archimedes burning ships with mirrors

betgo

Ad Honorem
Jul 2011
5,878
#11
Yeh, I don't see how something like that could have been made up. Also, Mythbusters tested it with 500 mirrors. What about with 3000 mirrors. The mirrors don't have to be held by soldiers. They could use men or boys too old or young for the military for that. They might have to make a bunch of mirrors quickly though.
 
Feb 2011
962
Scotland
#12
I saw the Mythbusters programme also.

I don't think it is completely fictitious.

I think it is simply far more likely that it was a cheap and easy method to deter the Romans (extremely nervous after the lever attacks pulling ships out of the water) from maintaining attacks. Maybe a rumour was spread suggesting such an attack was possible.
 
Aug 2014
4,013
Australia
#13
Yeh, I don't see how something like that could have been made up. Also, Mythbusters tested it with 500 mirrors. What about with 3000 mirrors. The mirrors don't have to be held by soldiers. They could use men or boys too old or young for the military for that. They might have to make a bunch of mirrors quickly though.
It is physically impossible for bronze mirrors, no matter how many you use, because bronze doesn't reflect the entire spectrum. You need modern mirrors and even then it can only work if you have a precise method of focusing all of the beams in one spot while simultaneously tracking the sun through the sky. You can't even get three people to do that. How do you suppose three thousand are going to do it?
 

betgo

Ad Honorem
Jul 2011
5,878
#14
It is physically impossible for bronze mirrors, no matter how many you use, because bronze doesn't reflect the entire spectrum. You need modern mirrors and even then it can only work if you have a precise method of focusing all of the beams in one spot while simultaneously tracking the sun through the sky. You can't even get three people to do that. How do you suppose three thousand are going to do it?
As I understand it, they tried to burn wood in Mythbusters, but wood ignites at about 180 C, whereas cloth at less than 100 C, so why not aim for the sail? Presumably there would be a big light at the point to aim at.
 

Corvidius

Ad Honorem
Jul 2017
2,426
Crows nest
#15
Even if it did work the defence is easy as all you need to do is make a frame to cover the front of the ship and place your burnished shields on it.

I do wonder if this story is actually the archetype of Reagan's "star wars" and was put about to scare the Romans, but over time has become "fact".
 

Dan Howard

Ad Honorem
Aug 2014
4,013
Australia
#16
As I understand it, they tried to burn wood in Mythbusters, but wood ignites at about 180 C, whereas cloth at less than 100 C
Cotton is one of the easiest natural fibres to ignite and a swatch has an ignition temperature of 201-304 deg C depending on the thickness (Reference: Mitchell N.D. National Fire Protection Association Quarterly. 1951;45(2):165-172.). The Greeks made sails from linen, which has an even higher ignition temperature. When the cloth is thick canvas, as is the case with sails, ignition temperature is higher again.
 
Last edited:
Mar 2018
591
UK
#17
It is physically impossible for bronze mirrors, no matter how many you use, because bronze doesn't reflect the entire spectrum. You need modern mirrors and even then it can only work if you have a precise method of focusing all of the beams in one spot while simultaneously tracking the sun through the sky. You can't even get three people to do that. How do you suppose three thousand are going to do it?
This reminds me of an interesting point: it is impossible to start a fire with moonlight using mirrors/lenses. You could have a lens in space the size of the moon and focus all the light from the moon onto a single point, and it still wouldn't be hot enough. The second law of thermodynamics prohibits it: you cannot use a body at a fixed temperature (in this case, the moon) to create a higher temperature (the one needed to start a fire). IF you could, you could use a mirror to make that hot point on the Moon, and you'd turn a body at uniform temperature into one with colder spots and hotter spots, which could in turn drive a heat engine. But it is impossible to extract energy from a single body at uniform temperature. That's, essentially, one of the formulations of the 2nd law of thermodynamics; the most inviolable of physical laws.
 
Feb 2011
962
Scotland
#18
As I understand it, they tried to burn wood in Mythbusters, but wood ignites at about 180 C, whereas cloth at less than 100 C, so why not aim for the sail? Presumably there would be a big light at the point to aim at.
When Roman war galleys went into action, they stowed their sails and used oar power alone.

Re Corvidius' point, as I have previously said, I think this entire subject is a psychological ploy used to frighten Roman officers already made nervous by Archimedes' weapons.
 
Mar 2017
75
France
#19
It is said that soldiers have used their bronze shields to achieve it on sails with concentration of thousands of soldiers on the defensive wall.
From my point of view it is possible.
 

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