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claymore | 11:19 Thu 03rd Jan 2008 | Science
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If you had to nominate mankind`s five greatest inventions what would you choose?
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wildwood, my apologies. I should have phrased that penultimate paragraph better. Nevertheless, it's not correct to think of a compass needle as being made of iron per se; it can be made of any iron mineral possessing magnetic properties

There are quite a minerals that contain iron not all of which are viable as ores. Magnetite is a valuable source of iron that occurs below ground and in surface deposits in parts of the world. Lodestone, a particular form of Magnetite which possesses polarity, will align itself in a N-S direction if allowed to move freely and is shaped suitably.

The only thing that bright spark needed to do was to fashion a piece of lodestone or other magnetic iron mineral into a needle shape and drop it on to a floating object on still water. The floating object could have been anything as long as it wasn't magnetic itself. The constant desire of the lodestone to settle in one particular direction would have set the ball rolling. There are probably many just as simplistic methods that would have brought magnetism to the attention of man although it would have depended on the iron containing mineral at hand because some are less magnetic than others. Because of this, there was no real necessity to smelt ores to get the iron out; the ore itself was capable of doing the job.

On the other hand, there is always the fable of Magnes to think about. This tells the tale of a shepherd who apparently discovered magnetite because he noticed that the iron nails in his boots and his iron staff stuck to ground while walking on his terrain. If you take this tale on board, you're soon in the realms of which came first out of the chicken or the egg!

I've often thought about another iron mineral in this context. Siderite, a type of iron carbonate, is very poorly magnetite under most conditions but when heated strongly it becomes magnetic. The ancestor who discovered this would surely have a tale to tell.
1. The nuclear bomb....preventing wars between major countries. Only defenceless countries can be attacked.
2. GM crops.....but only when they are available in 3rd world countries.
3. Headphones with noise limiters to block out surrounding noise.
4. The jet engine so that houses near to airports are easily affordable.
5. Motorways so minor roads can be used by bicycles and horses.
The pencil - so we could communicate and design all the other stuff.
The lever and the wheel - so we could move it around when we had built it.
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For dustypuss: A nanotube is a stucture of carbon atoms in the shape of a hollow tube. They have extremely novel chemical properties and are incredibly strong.

They promise to allow us to make materials with very unusual properties. They are highly conductive of electricity and are very compatible with biological molecules.

Already have been shown to work as catalysts in experiemntal fuel cells in place of expensive materials like palladium and platinum. Their potential to improve the output of ordinary zinc carbon dry cells has been demonstrated.

They have been synthesised into materials that are harder than diamond. They have been used to make the strongest materials known.

They have been successfully integrated into biological structures including living cells. The potential uses have only just begin to be contemplated.

They can have other molecules inserted inside the tube and have been used in experimental drug delivery techniques where the drug is kept inactive until it reaches its target.

However one could argue that they too are a discovery. Even though they were designed and manufactured by scientists it was recently discovered that they form spontaneously in the soot of a kerosene lamp.
can I change this thread around .What are mankind's 5 worst inventions what would you choose ( non military )

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