It was only when blacksmith and locksmith Hans Luter moved from Waldshut to Zurich in 1516 that he realised what a scarce commodity his talent was. He was one of the few people in his profession who knew how to build a clock movement. At that time, the profession of watchmaker did not yet exist.
Clocks – which then meant exclusively the large specimens installed in church towers and city gatehouses – were constructions that had a certain air of mystery about them. Anyone who could make an apparatus that moved uniformly over long periods of time without human intervention, simply had to be a magician. Luter was lucky in that there was no one in Zurich at the time who knew this secret. “For the sake of his art”, he was even granted citizenship of the city in the same year he arrived. He was later accepted into the Guild of Smiths for his achievements, a privilege that otherwise could only be bought at great expense and with good connections.
There was no shortage of work. Luter constructed at least 15 tower clocks, including one for St Peter’s Church. The last mention of him in the records of the city of Zurich was in 1543, when the clock in the Ketzerturm tower was inaugurated. His son Niklaus Luter was also granted his guild membership in the same year – it cost him 14 pounds and 16 shillings.
During all this time, Luter’s very first clock was ticking away in the church tower of Turbenthal. Today, it is one of the oldest surviving church tower clocks in Switzerland and can be found at the Beyer Clock and Watch Museum on Bahnhofstrasse, where it marks the transition from elementary clocks to mechanical timepieces. As it is in working order, the museum staff can use it to explain the principle on which every mechanical clock is based to this day.
When Luter moved to Zurich with his tools, the world was in a state of upheaval because, quite literally, a new time had dawned. With the arrival of the mechanical clock, a new way of calculating time came into force, which made itself heard with chimes in the city and in the country. It signalled the end of the ‘Horen’ (daylight hours of different lengths depending on the season) and also the end of the church’s monopoly on time.
Unlike sundials and other timepieces commonly used in that era, the mechanical clock could also measure and tell the time at night. Previously, the night watchman’s duties included regularly turning the hourglass and striking the bell from the tower to signal the full hour. As public clocks often had no hands or dials, their striking mechanism was all the more important. It takes up half the volume of our tower clock and is much more complicated than the going train, which only drives a single hand, as the minute had not yet been invented.
WOUND ONCE A DAY
Even though the cogwheel principle has survived into our day, the rest of the tower clock clearly dates from a different era. It consists of a wrought-iron frame, the individual parts of which are held together with wedges, similar to wooden furniture (screws were unknown back then). Both the going train and the striking train are driven by weights suspended on ropes wound around a wooden drum, which have to be wound up once a day. The drum of the going train rotates once an hour and drives the hour hand at one end via a reduction gear, which completes one revolution every twelve hours. The other end of the wooden drum transmits its power via a transmission to the toothed escapement wheel, which rotates 12.5 times faster.
As the striking mechanism is only activated once an hour, its only connection to the going train is a lever that is mechanically lifted once an hour by a cam on the wooden drum of the going train. Then the mechanism that has been waiting so patiently for its turn comes to life: a flyvane, which looks like a propeller, rotates to steady the speed of the striking train, while the lock disc counts off the correct number of strokes before a lever falls into a notch and brings the mechanism to a standstill for another hour. During the activation, a rapidly rotating cam presses a lever and releases it repeatedly as long as the lock disc lets it. At its other end is the clapper that used to strike the bell.
In the Beyer Clock and Watch Museum, the bell is missing so as not to cause a commotion in the whole building with every demonstration