The mechanism of the great tower clock of St Stephen's – Or: exact timekeeping is no easy matter

The tower clock made for St Stephen’s Cathedral in Vienna in 1699 weighed 700 kilograms. The first reports of a mechanical clock being installed in the cathedral date from the beginning of the fifteenth century; around 1500 a wooden clockface was put in place. However, for a long time the clock was so inaccurate that the the city council ordered timekeeping checks to be made. The master of the clock, who was responsible for putting it right, did this with the help of a number of sundials mounted on the cathedral.