Measuring time and time intervals is one of the primary functions of time telling instruments. Complications take watches beyond their regular time telling functions. As far as complications are concerned, chronographs easily top the list in terms of utility and popularity. Well, in a population where sporty pastimes are the order of the day, chronographs are indispensable!
Simply defined, a chronograph is a watch with two independent time systems, one for telling time and one for measuring the duration of time or having a stopwatch function. It indicates seconds (sometimes even sub-seconds!), minutes and hours.
It was in the year 1816 that Louis Moinet invented the chronograph, originally intended for tracking astronomical objects. Since then, this complication has come a long way. In addition to motor racing, the chronograph is also used in various other activities like piloting airplanes, diving, as well as submarine manoeuvring.
For specialized functions, specialized chronographs are used. Deep-sea divers for example, use chronographs where the basic functionality is the same as other chronographs. However, diving models have longer and more practical straps to wear over equipment. There is emphasis on waterproofness and also luminous dials for reading in the murky depths. Some of them are fitted with large bezels that have at least one luminous marking. At the start of a dive the bezel is rotated to place the marking at the extent of time allowed by the air supply giving the ability to very quickly determine how much time remains for safe diving. This feature can also be used to make quick calculations of distance travelled over time.
Watchmakers have taken precision in time interval measurement to dizzying levels of accuracy. In addition to the practicalities of use, the addition of a chronograph also makes the watch aesthetically appealing in its own way. The pushers or buttons on the case have their own style. Some wearers also appreciate the tactile pleasure of the movement of gears and levers every time the button is pressed. The mechanics of the chronograph fascinates them.
Many chronographs have a bezel, which is either fixed or can be rotated around the outside of the dial that is marked to specific scales to allow rapid calculations. The chronograph stop-start feature, in conjunction with the rotation of the bezel enables more complex calculations or repeated measurements for a series of calculations. Grand complications, that is, watches that have more complications within them, often have chronographs in conjunction with other useful complications.
A Double Chronograph or Rattrapante is a split-second timer or lap timer. It usually has two hands for the “split” time. A Lap timer is a chronograph function that lets the wearer time segments of a race. A Flyback Chronograph is one that is engineered in such a manner that when a second button is pushed while the chronograph timer is running, all the counters reset and immediately start again from zero. This feature was originally designed for pilots where split second accuracy is crucial for precise navigation. The flyback hand is a second hand on the chronograph that can be used to time laps or to determine finishing times for several competitors in a race.