So-called Viennese Crystal Clock

Rudolf II and the Art of Timekeeping
At his court in Prague the emperor promoted the close cooperation of astronomers, mathematicians and clockmakers. This resulted in pioneering works of precision engineering. The Planetary Clock was the first timepiece to depict the heliocentric planetary system while the Crystal Clock is the oldest extant timekeeping device with a second hand. Rudolf II acquired the Celestial Globe and the enamelled Table Clock in Augsburg.