A chronograph is a watch which in addition to showing the conventional time also measures and displays elapsed time. The system is driven by the movement of the watch and usually controlled by buttons on the side of the case which start, stop and reset the chronograph.
Chronographs usually have a large centre seconds hand with smaller dials for the elapsed minutes and hours. There are several different types of chronograph. The split seconds or rattrapante chronograph features two independently controlled second hands one of which has a ‘fly back’ facility. This type of watch can be used for measuring lap times involving multiple finishes.
Other types of chronograph are the single pusher which is controlled by a single button and the flyback chronograph which restarts as soon as it is returned to zero without the need to stop.