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The most famous spring is Cleopatra's Bath, which has crystal-clear natural spring water that gurgles up into a large stone pool, and is a popular bathing spot for locals.
BBC: Siwa: An Egyptian oasis
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He manufactures every component of his watches himself, except for the main spring and sapphire crystal.
FORBES: Magazine Article
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Friend vibrates a lead zirconate titanate crystal, and those vibrations twist a spring-like element attached to a rotor.
FORBES: Breakthroughs