The field of repeater watches is one of the most exclusive niches in the entire industry. The complexity of these mechanical marvels enabling them to engage with their wearers on multiple sensory levels is understandably awe-inspiring. But what is a repeater and what gave rise to this unusual enclave of watchmaking?
A repeater can strike the time on demand, playing audible sounds so the wearer can determine the hours and, in the case of minute repeaters specifically, the minutes also. This complication first became desirable before the advent of electrical lighting or the invention of luminous material, as it allowed the wearer to tell the time in the dark or low light conditions. It is also useful for partially-sighted or blind uses, as it communicates the time in a non-visual manner.
There are lots of types of repeaters, communicating different amounts of information in different ways. As the accuracy of the striking mechanism improves, so too does the complexity of the movement and, as a result, the rarity and cost of the piece.
Quarter repeaters are a relatively "basic" form of a repeater mechanism, striking first the hours in one tone, and then the number of quarter hours since the hour in a different tone. So, for example, 02:16 would be expressed by two strikes in the hour tone, followed by one strike in the quarter-hour tone.
Half-quarter repeaters are quite uncommon, perhaps due to the unusual increment recorded by their second tone. Half quarter repeaters add one strike to the second tone for every seven and a half minutes that have elapsed since the hour. 02:16 would, therefore, be expressed as two strikes of the hour tone and two strikes of the minute tone.
A much more intuitive version of the repeater is the five-minute repeater, which strikes first for the hours and then for the number of five-minute increments elapsed since the hour. In this case, 02:16 would be sounded by two strikes of the hour tone and three of the minutes.
For up-to-the-minute accuracy, a minute repeater is needed. Here, our random example time of 02:16 would be communicated by two strikes of the hour tone, one strike of a special quarter tone, and one high-pitched strike of a third tone.
Decimal repeaters, which strike for ten-minute intervals and minutes thereafter instead of 15-minute intervals followed by the minutes are very rare but do exist. 02:16 would equate to two-hour strikes, one decimal strike, and six-minute strikes, all in different tones.
Repeaters are excellent examples of a watchmaker's mastery of the mechanical realm, but they do come at a cost. As some of the most revered pieces in the history of horology, repeaters are rarely seen in the wild and are often kept locked away in museums or personal safes in light of their immense delicacy and value.