Sunday, October 23, 2005

The Archimedes Mirror Battle Tactics Reproduced (sort of)


By Elaine Meinel Supkis

The University of Arizona (my school, yaboo!) and MIT decided to try reproducing the famous Achimedes mirrors burning ships battle tactics. Seemingly, it failed. I will explain why.

From Yahoo:
It wasn't exactly the ancient siege of Syracuse, but rather a curious quest for scientific validation. According to sparse historical writings, the Greek mathematician Archimedes torched a fleet of invading Roman ships by reflecting the sun's powerful rays with a mirrored device made of glass or bronze.

More than 2,000 years later, researchers from the Massachusetts Institute of Technology and the University of Arizona set out to recreate Archimedes' fabled death ray Saturday in an experiment sponsored by the Discovery Channel program "MythBusters." Their attempts to set fire to an 80-year-old fishing boat using their own versions of the device, however, failed to either prove or dispel the myth of the solar death ray.

The MIT team's first attempt with their contraption made of 300 square feet of bronze and glass failed to ignite a fire from 150 feet away. It produced smoldering on the boat's wooden surface but no open flame. A second attempt from about 75 feet away lit only a small fire that burned itself out.
An 80 year old fishing boat isn't what these ancient ships were. For one thing, I know old boats well. If they have been sitting idle for many years, they are wet with rain water collecting within the wood, ie, rotten. Ever try to start a rotten fire? I have.

It is very hard. The punkier the wood, the harder it is to set it on fire, outdoors. If it is stored indoors, it will be dryrot which burns easily but I assume this old boat was lying outside, untended, and thus, wet inside. All boats left ashore and untended tend to get wet rot.

Further, how did the Romans or everyone keep their boats water-proof? The ancient mariners who ceased using hide boats or wooden canoes had to deal with sealing the planks used to build ships. For this, nearly everywhere, they used pine pitch in the north or in the Middle East...oil. So, from my experience with dealing with old peices of wood from piers and ships, they are oil soaked if they are more than 100 years old. The older, the more oil soaked. Up until vanishes were used instead which is about 1900.

So...the boat used in this experiment probably was a varnish covered boat that lost its varnish, not an oil soaked boat that was very much afloat and probably "primed" just be for launching to go to war.

Further, what if the part set afire was the sail? They used sheep's wool sails and this is more burnable than wood and further, probably, since it was laid down on the decks of the oily boats, wool soaks up oil, too. Thus, it ignites.
In "Epitome ton Istorion," John Zonaras wrote: "At last in an incredible manner he burned up the whole Roman fleet. For by tilting a kind of mirror toward the sun he concentrated the sun's beam upon it; and owing to the thickness and smoothness of the mirror he ignited the air from this beam and kindled a great flame, the whole of which he directed upon the ships that lay at anchor in the path of the fire, until he consumed them all
Since the ships were at anchor, and since the mirror array was overhead, the beams would have not been concentrated on the hulls but rather on the decks where the sails laid like some candle wicks, perhaps.

My family has a fondness for this story because of my parent's work on solar arrays and multimirror telescopes. Both of my parents collect pictures about this event. We talk about it. It astonishes me that the students doing this trick didn't consult with authorities about Roman ships, first.

And next: the story about the turtle dropping on poor Archimedes' head. Any mathematicians willing to try out that story?

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Global Warming Causes More Snow To Fall but Also More Glaciers to Melt


By Elaine Meinel Supkis

Global warming has complex features. People who want to believe it isn't happening will clutch at any straw that seems to prove their point. Increasing snowfall in Greenland and Antarctica cheers them up but this is a false reading of the data.

From CNN:
Greenland's ice cap has thickened slightly in recent years despite wide predictions of a thaw triggered by global warming, a team of scientists said on Thursday.

The 9,842-feet thick ice cap is a key concern in debates about climate change because a total melt would raise world sea levels by about 7 meters. And a runaway thaw might slow the Gulf Stream that keeps the North Atlantic region warm.

But satellite measurements showed that more snowfall was falling and thickening the ice cap, especially at high altitudes, according to the report in the journal Science.

Glaciers at sea level have been retreating fast because of a warming climate, making many other scientists believe the entire ice cap was thinning.
As my schematic drawing above shows, there are several forces at work. I live on a mountain in the northeast. There is a very simple rule of thumb up here: if the winter is warm, we get a lot more snow. If it is a very cold winter, we get less snow, less volume per gallon of water because the snow is hard pack, small crystals, and it doesn't melt in the sunlight. We get lots of sun in cold winters, in my passive solar heated house, it can be way below zero and I don't need heat because nearly always, it is very sunny, the sky a deep, dark blue and you can go out on my deck with a swimming suit on and sunbathe! When I was visiting relatives in the Alps back in the sixties, I remember the doing exactly that, sunbathing in the winter.

But wet, cloudy, warm winters can accumulate four to six feet of snow on my mountain. This melts really fast once spring comes even if it remains cloudy. The cold years, the sun can be shining in April and the ground remains stubbornly frozen, if the air temperature is 20 F degrees or less, it doesn't matter how much the sun shines, nothing melts. And we had springs where it didn't warm up until May to my despair. The worst winter ever was -40 F degrees at one point and less than one foot of snow fell the entire winter!

In the Great Ice Ages, much of the world's water that wasn't ocean was locked in giant glaciers. The snowfalls were tiny each year and the sun shone fiercely but nothing melted. What little snow fell, accumulated since it didn't melt. The pressure from this snow compressed into great ice sheets.

Today, at the base of the ice sheets, the ice is melting because even at night, it is warm enough to melt it. The sun shining on the surface has little effect but the warm air at the base does. This is why glaciers can grow at the top and shrink at the bottom simultaneously.

This is no mystery. Global warming means desertfication at the equator which is easy to see as the great jungles that thrived during the Great Ice Ages are now shrinking. The huge deserts that grew throughout this interglacial cycle are growing, not shrinking. The band where water falls is moving north, not to the equator. Even here on my mountain up north, I feel the effects of all this, for instead of a temperate climate with the same amount of rain each month, we get weird dry/wet cycles that have no season at all. It will rain like crazy for four or five months then be totally dry for several months, like this year, we went for three months with only spotty rain storms. Then in October, it rains over the entire upper half of the continent nearly nonstop. We had over 12" of rain in less than three weeks which is crazy! Storms dumping 7"-12" are pounding us.

The same in the hurricane areas. More and more hurricanes dumping in between total dryness. This flood/drought cycle is very much an artifact of global warming. Greenland is of particular interest because it is part of the weather flow I live in, namely, many storms that hit me, hit Greenland. So a 10" dump here translates into 8' of snow in Greenland if the same storm system passes over that continent.

In conclusion, the data pointing to serious global warming are all in the yellow zone heading towards the red zone. If we have significant volcanic action, and in five years, this is very likely thanks to the earthquakes changing the relative position of Sumatra, we will have colder/wetter years due to volcanic dust. But outside of that, global warming is definitely underway.

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