chronograph

A chronograph is a timekeeping device that combines a clock with a stopwatch function, allowing the measurement of elapsed time without affecting the main time display. The term derives from the Greek chrono (time) and graph (writing), meaning a device that records time.

The concept emerged in the early 19th century. Louis Moinet is credited with creating one of the first mechanical chronographs around 1816, while Nicolas Mathieu-Rieussec developed an early ink‑pen chronograph in 1821 to time horse races. Over time, wristwatches incorporated chronograph mechanisms, becoming a standard complication in many brands.

In wrist chronographs, a set of pushers starts, stops, and resets a central chronograph hand that measures elapsed time, while additional subdials display running seconds and minute (and sometimes hour) counters. Modern models may be automatic or hand‑wound and may include flyback or one‑button (mono‑pusher) configurations.

A monopusher uses a single button to control all functions; a rattrapante (split‑seconds) chronograph records two times simultaneously with a second stopping hand. External scales such as the tachymeter measure speed over a fixed distance, and the telemeter indicates distance based on the speed of sound.

Beyond watches, chronographs have been used as portable timing instruments in sports, aviation, and science. In modern horology they remain a popular complication for precision timing and the demonstration of mechanical engineering.