Science & Discovery
74 sourced historical stories, arranged by subject.
Science & DiscoveryZhang Heng's instrument aimed to identify an earthquake's direction
Historical accounts describe Zhang Heng's earthquake instrument as a mechanism that released a bronze ball from a dragon's mouth corresponding to a direction, signaling where a distant earthquake had occurred.
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Science & DiscoveryA zipper's slider joins two rows of teeth
A zipper uses a slider to bring together or separate the successive teeth along two sides. Early patents underwent repeated improvements before the structure became convenient for clothing and luggage.
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