Astronomical clock, Chinese, 1088.
© Science Museum / Science & Society Picture Library
Model (scale 1:48) of a Chinese astronomical clock, copied from Su Song's 'New Design for a Mechanised Armillary Sphere and Celestial Globe' (1092). Su Song (1020-1101) was a Chinese astronomer and inventor who was ordered by the emperor to construct a complex armillary clock. The original clock-tower was 37 feet high overall. The clock mechanism drove the armillary sphere mounted on top of the tower, while inside the tower a celestial globe was rotated once in a sidereal day by the clock. The time of day was shown by 'jacks' appearing in apertures in the sides of the tower and was also sounded audibly.