The chronograph It is a useful tool for the measurement of a precise time interval . It is configured as chronograph watch when it is accompanied by the time function and in some cases the date function.
In most cases, the passage of time is recorded thanks to specific counters equipped with hands, arranged inside the dial, which quantify the interval measured in seconds, minutes and hours. In addition to the presence of these sub-dials, the central hand marks the time on a perimeter scale divided into tenths or hundredths of a second.
HOW THE CHRONOGRAPH WAS BORN
The term chronograph comes from the Greek Khrónos 'time' and gráphō 'to write'. The action of graphically marking an interval of time was perfected with the chronograph of Nicolas Matthieu Rieussec in 1821. The instrument was able to mark a period of time with a line of ink on a disk, most often useful for determining the times of speed races. The name itself in French “compteur de chemin parcouru” (counter of the distance travelled) and the characteristics of the instrument give the visual suggestion of a graphic sign useful for defining a real concrete writing of time.
But the first “thirds counter” (so called without being officially defined as a chronograph) was built by Louis Moinet in the shape of a pocket watch in 1816. The model already featured the now iconic three counters of the seconds, minutes and the button with the functions of starting, stopping and resetting the main hand to 12 o’clock.
The composition of the dial, consolidated over more than 200 years, is accompanied by a perimeter scale with a central hand useful for determining the time divided into tenths or hundredths of a second.
The explanation of the dials of a chronograph is relatively simple. In most models the number of counters is two or three. The time interval indicated by each of them varies depending on the chosen unit of time (for example, there are counters that indicate 60 or 30 units, understood as seconds and minutes). In these cases the sub-dials with small seconds and minute counter can measure maximum times ranging from half an hour to an hour. In some cases the time intervals can reach 12 hours when an auxiliary dial with hour function is inserted.
The hands of these sub-dials are usually operated by two pushers housed in the case, above and below the crown (two o'clock and four o'clock respectively) with the function of starting/stopping and resetting the seconds hand.
These three functions can be concentrated in a single pressure point which characterises the variant called single-pusher chronograph .
The idea of using a watch as a tool for measuring time intervals is developed and made more complex with the integration of various graduated scales placed on the outer perimeter of the dial for better reading integrated with the second hand. The tachometric scale , in addition to being an indicator that measures the speed traveled along a predetermined distance, was, especially in the past, flanked by other measurement scales. In a vintage chronograph , as well as in recent models with a retro taste, we can in fact observe the telemeter, useful for measuring the speed of sound, used in the ballistic chronograph to define the distance of a bombing and that of thunder in meteorology. In the medical field we find the pulsometer, effective in determining the heart rate per minute by recording the beats in a few seconds.
COMPLICATIONS AND CHRONOGRAPHS
Finally, it is useful to remember two notes additional complications to the chronograph : the Rattrapante and Flyback functions.
There rattrapante complication allows you to use a single chronograph , instead of two, to count two distinct time intervals , such as in the case of a race between two cars.
The two hands can be started and stopped at different times thanks to the introduction of a third pusher. They can be realigned during the measurement of an interval. The movement of this particular recovery of the central hand has given its name to this complication; with the term rattrapante, from the French verb rattraper , literally means to recover, to reach.
There Fly-back complication facilitates the measurement of time intervals. It became popular among pilots from the 1930s onwards who were looking for a speed of calculation useful for measuring their flight plan. With this chronograph, you can observe a time interval by stopping, resetting and restarting the main hand with a single press and subsequent release of a single button.
In-depth analysis by Daniele Beacco
Watch Advisor
