Thus there are complications that refer to visual indications, complications that comprise astronomical indicators and finally complications that have acoustical indicators. The former category includes: simple chronograph, counter chronograph, double chronograph, independent second hand chronograph and jumping second hand chronograph.
The second group, which refers to astronomical indicators comprises: simple calendar, perpetual calendar, annual calendar, which is not a common feature, moon phase indicator and equation of time. The last category includes several acoustical indicators. Among them there are: alarm; quarter, half-quarter, five-minute, minute repeaters and passing strike.
All in all the alarm function represents a very old mechanism. This particular acoustic indicator can be programmed for twelve or twenty four hours. Repeater is a term that watch-experts use to characterize a watch equipped with a strike or chime. This makes it possible for the timepiece to chime hours on demand and repeat as often as one desires. A particular type of repeater shows the precision of a specific watch. Thus the more often a watch is able to strike the more precise is the timepiece itself.
For example, a quarter repeater strikes on demand both hours and quarter hours that have already been passed. During chiming the repeater uses two bells. There's one low tone for the hours and one high tone for the quarter hours.
Apart from the quarter repeater the half-quarter repeater function is the one that strikes both the hours and the quarter-hours and at the same time when a half quarter passes it strikes an additional high tone. There's also a five-minute repeater which strikes the hours with a low tone and in addition it is able to strike on demand each five-minute interval.
Minute repeater is an acoustical indicator that strikes the hours and quarters just like the quarter-repeater. But in addition, it strikes the minutes that have exceeded the last quarter. These are signaled with several rapid strikes made on the high toned bell. Thus is the time is 12:59 the repeater will strike 12 low tones, and afterwards three series of high-low tones. In the end you will hear 14 rapid high tones.
The passing strike function is the one that in an automatic mode signals the hours and quarter-hours. The hour is repeated at each quarter. There's a special device for indicating hours and minutes on demand. However, there's a limited number of demands. The chiming feature may be turned off by demand.
