What Is a Chronograph?
A chronograph is a timepiece capable of measuring discrete elapsed time units as well as telling time in a 12-hour format. In such a watch, each of these two separate time-keeping functions operates independently. This means that one typically contains a mechanism for regular time-keeping as well as a separate movement for the stopwatch, or elapsed time, function. A chronograph should be distinguished from a chronometer, which is a timepiece that is officially certified for its high degree of accuracy.
The time-keeping function of a chronograph is performed by traditional hour and minute hands typically used for indicating the time. Chronographs may come in a variety of forms. Some are stand-alone mechanical timepieces with independently operated mechanisms for measuring each discrete unit. Operation of the elapsed timer does not interfere with the running of the 12-hour time-keeping function. Most modern chronographs are wristwatches that are capable of measuring elapsed seconds, minutes, and hours. Some wristwatch models are digital, while others combine mechanical movements with digital displays.
Some chronograph models incorporate a mechanical or battery-induced movement for running the 12-hour time format, while the elapsed timer feature is displayed digitally. Some chronographs show both 12-hour timekeeping as well as the elapsed time digitally, in small, rectangular, liquid crystal display windows. Mechanically-powered chronographs have separate rotary sub-dials, each with a single hand that indicates either the hour, minute, or seconds of elapsed time. As soon as the seconds sub-dial reaches the one-minute mark, the other minute sub-dial advances forward in single minute increments. When the minute sub-dial reaches 60 accumulated minutes, the hour sub-dial advances to the one hour elapsed position.
Modern chronographs often have buttons that protrude from the watch case which are used to trigger the various elapsed time functions. Usually, one button activates the elapsed timer function, while another stops it, so that an elapsed time can be measured on the sub-dials. Pushing one or the other buttons generally resets all the hands on each of the sub-dials back to the initial starting position. The degree of accuracy of the elapsed time readout on a mechanical chronograph is determined, in part, by the gradations or number of incremental units marked on each of these sub-dials. Some digital chronographs may offer a more precise, more readable measurement of elapsed time because certain types may be capable of recording, as well as displaying, time in fractions of a second.
Written by John Kinsellagh
