Su Song's clock tower continues functioning

1279

In Kaifeng, the elaborate water-powered astronomical clock tower built by Su Song in the previous century continued to strike the hours, its chain-drive escapement silently announcing the heart of modern horology to any Mongol official patient enough to notice. The tower's mechanism, which rotated an armillary sphere and a celestial globe in synchronization with the heavens, represented the most advanced timekeeping technology in the world.