A repeater is a complication in a mechanical watch or clock that audibly chimes the hours and often minutes at the press of a button. There are many types of repeater, from the simple repeater which merely strikes the number of hours, to the minute repeater which chimes the time down to the minute, using separate tones for hours, quarter hours, and minutes. They originated before widespread artificial illumination, to allow the time to be determined in the dark, and were also used by the visually impaired. Now they are mostly valued as expensive novelties by watch and clock enthusiasts. Repeaters should not be confused with striking clocks or watches, which do not strike on demand, but merely at regular intervals.
How they work
Repeater clocks often had a cord with a button on the end protruding from the side of the clock. Pulling the cord actuated the repeater mechanism. This was called a pull repeater. Repeating carriage clocks have a button on the top to activate them.
Early watch repeater mechanisms were powered by the watch mainspring and were actuated by pushing on the crown. The disadvantage of this is that using the repeater often ran down the mainspring. Later ones are activated by pushing a slide along the side of the case. This winds a separate spring to power the repeater. Releasing the slide releases the spring, and its force as it unwinds moves the repeater mechanism through its chiming sequence.
The gongs are made of long hardened steel wires that are coiled inside the watch case. Tiny hammers actuated by the repeater mechanism strike them to make the chiming sounds. Some of the complex repeaters, such as the minute repeater, need to produce three different sounds, to distinguish hours, quarter hours, and minutes in the striking sequence. Since it is difficult to fit three bulky wire gongs into a watch movement, virtually all repeaters use two gongs, made from the two ends of a single length of wire supported in the middle, and if a third sound is needed it is made by striking the two gongs rapidly in sequence, first the high tone and then the low: "bing-bong".
The term 'repeater', without qualifiers, usually means an hour repeater. On pressing the lever or button, the repeater strikes the number of hours that have passed since 12 o'clock on a gong. This is the only type of repeater that needs a single gong. No distinction is usually made between AM and PM, so whether the time shown is 2:00am, 2:17am, 2:59am, or 2:59pm, the repeater will give the same signal: "bong, bong".
The quarter repeater strikes the number of hours, and then the number of quarter hours since the last hour. The mechanism uses 2 chimes of different tones. The low tone usually signals the hours, and the high tone the quarter hours. As an example, if the time is 2:45, the quarter repeater sounds 2 low tones and after a short pause 3 high ones: "bong, bong, bing, bing, bing". Alternatively, some use a pair of tones to distinguish the quarter hours: "bong, bong, bing-bong, bing-bong, bing-bong"
The half-quarter repeater can sound the time to half a quarter hour, or 7 1/2 minutes. It strikes hours and then quarter hours, like the quarter repeater, then it uses a single tone in order to signal if more than half of the current quarter hour has passed. For example, if the time is 3:41 the mechanism will strike 3 low tones ("bong") to represent 3 hours, then 2 sequence tones ("bing-bong") to represent 2 quarter hours, then one high tone ("bing") to indicate that more than half of the third quarter hour has passed.
The five minute repeater strikes the hours and then the number of five-minute periods since the hour. The mechanism uses a low tone for the hours and a high tone for the minutes. For example, 2:25 would be struck as: "bong, bong, bing, bing, bing, bing, bing".
The minute repeater works like the quarter repeater, with the addition that, after the hours and quarter hours are sounded, the number of minutes since the last quarter hour are sounded. This requires three different sounds to distinguish hours, quarters, and minutes. Often the hours are signalled by a low tone, the quarters are signalled by a sequence of two tones ("bing-bong"), and the minutes by a high tone. For example, if the time is 2:49 then the minute repeater will sound 2 low tones representing 2 hours, 3 sequence tones representing 45 minutes, and 4 high tones representing 4 minutes: "bong, bong, bing-bong, bing-bong, bing-bong, bing, bing, bing, bing"
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