Watch is a timing device, and also indicate the time of measurement precision instruments. Watches are usually less machine the size difference. According to international practice, the movement more than 80 mm in diameter, thickness of more than 30 mm of a bell; a diameter of 37 to 50 mm and a thickness of 4 to 6 mm, known as pocket watch; the watch diameter 37 mm; diameter no greater than 20 mm or machine heart area is not more than 314 mm2, called the female form. The watch is invented by man smallest, most rugged, one of the most sophisticated machinery.

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拍攝者： Jingaiping