In Prague this week. The ‘old city’ section is a treat for history of science buffs. We managed to get a perch in front of the medieval astronomical clock in the Square. This is the oldest operating clock in the world, and the third oldest overall, surviving from the fifteenth century. The clock strikes on the hour, but was more ambitiously designed to follow the phases of the moon and the passage of the sun through the Zodiac year around. Note in my video (about forty seconds in), the chimes begin with Death, personified by the skeleton, ringing the bell, while the apostles pass by the opening windows above.

(continued at Forbes….)