How it works: Minute repeater
Today, we can hardly imagine life in a time when at night, due to it being dark, there was no option of telling the time just by touching a cell phone or a digital alarm clock by the bed: during the night, the passage of time was told only by the church bells that chimed the characteristic melodies once every fifteen minutes or once every full hour. The master watchmakers managed to build in this simple, but very complex solution, first into wall clocks, then into pocket watches and finally also into wristwatches.
So that the owners of the watches with this – at first – quite rare complication would not be bothered by the continuous chiming of the watch, they developed an interesting solution that enables us to “call up” the information about the time, and they called it ‘a repeater’.
A sound that is loud and – above all else – clear enough, is one of the most important demands that a quality watch with a minute repeater must meet. While constructing and assembling such mechanisms, the master watchmakers deal with extremely delicate components, a lack of space within the wristwatch case and an extremely small amount of power that is available for the strikes of the tiny hammers. The case material also greatly influences the sound: for example, titanium or steel, due to a lower density, “pass” more sound than gold or platinum, and many amplify the sound with various openings in the case.
The minute repeater mechanism is activated by pressing the sliding lever, which winds up a tiny spring that contains just enough power for the hammers to chime the time-telling melody once. If we do not put enough pressure on the sliding lever, the hammer strikes are not activated, since the complication could only chime a half of the necessary strike set due to a lack of power. A fully wound spring thus activates a mechanism, which in accordance with the position of several levers and geared wheels determines the current time and translates it into a series of hammer strikes upon two gongs: tuned wires that are set just at the rim of the case.
Each of the gongs is tuned to a different sound and so, for example, with a typical minute repeater, a chime of the gong with a lower tone stands for one full hour, a sequence of chimes in a higher and then lower tone stands for a quarter of an hour, and every chime in a higher tone counts the individual minutes within the fifteen-minute interval. If we activate the complication when the time is 4:55, it will first chime four chimes of the lower tone, then three chimes of high-low tone sequences and ten chimes on the higher-toned gong.
So that the gongs chime in exactly the right tone, they need to be precisely tuned: the watchmakers often adjust the length of the gong for days or even weeks, so that when the hammer strikes it, it sounds the perfect chime. Because the gongs are attached only on one point, the master watchmakers must ensure that there is appropriate space, so that when the gongs vibrate due to the strikes, they do not touch other components or even the case: that would break the chime. What is also tremendously important is the ratio between the weight of an individual hammer and the firmness of the string, which must provide for the precisely strong enough strike to an individual gong.
Today, the watch minute repeater remains one of the least common complications: it is made only by the most experienced watchmakers, and often it is a part of mechanisms with the classic “triple complication”, which under a single dial entail also the chronograph and the perpetual calendar. Even so, this is one of the most prestigious and admirable complications both for the enthusiasts and for the collectors, which can hardly be overshadowed by other characteristics of a timepiece.