How are Crystals Formed?

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Crystals are solids found in nature that have a regular three-dimensional shape. They come in an almost endless variety of sizes and shapes. All crystals have an orderly shape due to the internal arrangement of the atoms, ions or molecules making up the solid. Crystal formation can be watched easily at home. Add sugar to water and let it dissolve. Now heat the water solution and let the water evaporate. Gradually, all the water evaporates leaving the crystals of sugar behind.

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When were the First Mechanical Clocks Made?

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The first mechanical clocks are believed to have been made in China in 1088 AD. Later in 1200s, they were first made in Europe. Such clocks made in Europe were driven by a weight on the end of a cord wound round a drum. As the drum rotated, it turned the hands of the clock. The earliest known clock was made in Spain in 1276 AD and the oldest mechanical clock that still works is in Salisbury cathedral in Britain. It was made in 1368. These clocks had devices called escapements to keep the hands turning at the correct rate, so that the clocks depicted the correct time.
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