The first chronograph in history, the “Thirds counter”, was created by Louis Moinet in 1816 and was the first pocket watch with a central hand capable to rotate in one minute and to be activated, stopped and resetted with a pusher.
However, the term “chronographe” was introduced a few years later by Nicolas-Mathieu Rieussec that patented a system where a little ink tank was fitted into the measuring hand, recording the time interval on a white dial, allowing it to be measured.
Actually, the name “chronograph”, as explained to us by the Director of Brand Heritage of Omega, Petros Protopapas, is a common mistake that derives from the invention mentioned above. Today’s chronographs, to be in accordance with the Greek etymology, should in fact be called “chronoscopes”. To find out more, I leave you the link to our video!
The real revolution came in the 30s, when the first wrist chronographs were patented, adding a module to the mechanism capable to operate independently the start, stop and reset functions.
Over the years, the countless uses of the chronograph let this famous and beloved complication to spread over people that really uses it for technical measurements as well as who just aesthetically enjoys it.
Technical basics
Many types of chronographs were developed, but we think it’s better to first see the fundamentals of chronographs to understand more complicated ones.
The mainly involved components are the watch seconds wheel and the chronograph seconds wheel. While the first is always spinning, the chronograph seconds needs to be activated and stopped when required. A crucial part in the operation of a chronograph is the way the connection between running seconds and chronograph’s, called clutch, is manufactured.
The clutch can be lateral or vertical.
The lateral clutch works thanks to a pusher-operated lever. To the pressure, the lever moves a mechanism that connects a wheel from the running seconds to the chronograph’s, activating them. This is the less precise clutch, because when the lever gets pushed, a little “jump” can occur due to wheel alignment.
The vertical clutch, instead, works like an actual clutch. Second wheels are overlapped and, when the pusher is pressed, the graft is set by contact instead of interlocking. This allows for a smoother operation and less wear of the components, compared to lateral clutch.
Another crucial part is the shunt system. In other words, the procedure as all the different function levers are managed. Here again, we can find two systems.
Column wheel
It’s considered to be the best shunt system, except being very technically advanced, rises the prestige and the collectors’ praise because of its manufacturing complexity. It works via a Column Wheel, a cylindrical component with six trapezoidal “columns” on the top, used to manage the chronograph’s different levers related to the functions.
This system makes the engagement of the chronograph really smooth and needs for less pressure compared to cams.
Cam shunt
A cam shunt works thanks to cam-operated levers. The number of components involved is similar to a column-wheel mechanism but requires less building precision and lower manufacturing and servicing costs.
The best mechanism surely is the column wheel with vertical clutch, while the most budget-friendly is the cam shunt with lateral clutch, lacking in precision because of the “jump” caused by the joining of running seconds and chronograph’s gears.
Different types of chronographs
Chronographs are important calculation tools that need to provide the highest precision possible. This is why, over the years, many different versions were born, to adapt over a wide range of uses. Let’s see some of them.
Flyback
Thanks to Longines, back in 1936, the ancestor of modern flybacks was patented. This “complication’s complication” allows to measure sequences of time very quickly, without manually resetting the chronograph. Usually, when the chronograph is running and the reset pusher is pressed, the measuring instantly starts back from zero.
Rattrapante
As seen in a previous article, the first rattrapante mechanism was created by Louis-Fredric Perrelet in 1827.
This particular chronograph comes in handy when two events with the same beginning but not the same end needs to be recorded. Two chronograph second hands are overlapped. When simultaneously started, a pusher allows to stop one hand while letting the other keeping its measurement. Reactivating it, the first hand will match the unstopped one.
The need to manage two second hands makes it an important and complex complication to deploy because of many precision errors that can occur, for example the faulty alignment of second hands.
Inside the rattrappante family, we can find the monorattrappante. It features a single hand capable to stop and retrieve the lost seconds when reactivated.
Monopusher
The monopusher chronograph features a single pusher that, in sequence, allows to operate all the functions of start, stop and reset that are usually managed through two different pushers. A distinctive feature is in the position of the pusher, that can be found at 2, 4 or, in some cases, in the crown at 3 o’clock.
Regatta chronographs
Not less important, these chronographs are used by skippers to calculate, in the minutes before the start, the right side to start on the base of the start line and wind direction.
They feature a particular countdown pre-setted system that is activated by the chronograph and displays the remaining time from SET to START, usually with analog numbers or bright-colored slots to ease the read. They allow to calculate optimal starting strategies interacting with the graduated bezel.
“Central” chronograph
Introduced by Singer Reimagined in 2017, it’s focused on the high legibility of the chronographic feature. It was born from a massive work by the team, to create a movement that allows to tell the time peripherally (on the sides of the dial) with two rotating discs, and the chronograph’s records on the center.
“Absolute Clutch” Monopusher by De Bethune
As you can read on our article on the new collection, De Bethune’s DB28 Maxichrono holds a record: a monopusher chronograph with 5 central hands. This allows to have all the chronographic measures in the center, very quick to read. All is possible thanks to the Absolute Clutch, a combination of the previously seen clutches.
Zenith Defy’s Double Tourbillon Chronograph
This new chronograph introduced by Zenith in 2019 Basel Fair, features the hyper sophisticated automatic chronograph movement El Primero 9020 that, thanks to its two tourbillons, is capable to measure precisely up to a tenth of a second. This is possible thanks to two separated tourbillon escapements:
The watch works at a frequency of 36.000 vph and the tourbillon completes one turn in 60 seconds, while the chronograph, world’s quickest, works at a whopping 360.000 vph frequency, completing a turn every 5 seconds and letting the chronograph seconds hand to complete a turn per second.
Eberhard Chrono4
This watch, born in 2001 and protected by a patent that only allows Eberhard to produce this complication, overlap the chronograph’s counters and the running seconds subdial. Trivial at first sight, to manufacture this movement many years and the stubbornness of Palmiro Monti, brand’s CEO at the time, were needed.
Based on a heavily modified ETA 2894-2 automatic chronograph modular movement, eight gear trains were added to power the four subdials that (from left to right) display minutes, hours, chronograph’s 24 hours and running seconds.
Even though technology made this function almost obsolete to the wearer, the chronograph embodies one of the foundations of horology and one of its spread keys over the last century. Just think about the link between the chronograph and motorsports to understand how a whole item can be revolutionized by “just a hand”.
Brief Off-topic!
The two most iconic models easily are the Rolex Daytona and the Omega Speedmaster. For their glorious history and characteristics, they are the most known chronographs ever and, even though powered by different movements, their functioning is the same.
Now, let’s see how to operate a chronograph and how to read the different scales we can find in these watches.
How does a chronograph work?
The pusher at two o’clock activates and stops the chronographic measurement, while the second pusher at four is used to reset the measurement when the chrono is stopped.
The counters
To ensure a precise measurement of timespans over one minute we can rely on sub-dials that usually allow us to record up to 12 hours.
The counters or sub-dials are usually three. The minutes one (at 3 o’ clock) has a 30 minutes scale and every two rounds, we’ll see the hours counter (at 6 o’ clock), divided in twelve parts, moving one hour forward. The third counter, with a sixty-seconds scale (at 9 o’ clock), is for the running seconds, independent from the chronograph and always moving.
Tachymetric scale
It’s surely the one that made this complication famous. We use it to measure the mean speed over a predetermined length (usually one kilometer or a mile)
To do so we find, on the bezel or on the dial, a scale of mean speeds of the measured object. The more time it takes, the lower the reading is. Practically, the measurement is started when the object crosses the beginning of the reference distance and stopped when the end is reached. The average speed is displayed on the scale by the seconds hand.
If the speed is under 60 uph (units per hour) there are some scales (not featured in the Daytona or the Speedmaster) that allow the reading of lower speeds on a “spiral scale” (also known as “snail”).
Telemetric scale
The telemetric scale is used to determine the distance of a visible and audible phenomenon.
It is said to have been used during warfare to figure out how to position cannons to hit a target. When the flash caused by the cannon was seen, the measurement was started and, when the projectile touched the ground, it was stopped. Another unfortunate occasion of use, always in war, was to measure the distance of enemy fire by measuring the time that elapsed between the flash and the sound of the shot.
Nowadays it can be useful to calculate the distance of a lightning bolt from the observer, using the difference between lightning and thunder. This happens thanks to the difference in speed between sound in the air (about 345 meters per second) and the speed of light (300,000 km per second).
Pulsometric scale
Pulsometric scales are prefect for doctors or everyone who needs to quickly measure someone’s heart rate. On the dial we usually find the number of beats to record after the beginning of our measurement: in the picture we can see “gradué pour 30 pulsations”, French for “calibrated for 30 pulsations”. When the chronograph is activated, the beats are recorded (usually 15 or 30) and then stopped. The seconds hand will tell the beats per minutes of the patient.
Usually, professional pulsometric watches are produced as monopusher chronographs to ease the use to who, besides holding the chronograph, needs to measure the patient’s beats and thus has only one free hand.
Asthmometric scale
Less precise therefore less common, the asthmometric scale works exactly as the pulsometric. Instead of recording the heartrate, it measures the patient’s breaths per minute.
Decimeter
This peculiar scale allows to divide a minute in one hundred parts, easily converting time into decimals. Decimal time conversion was used in scientific and industrial fields to ease the calculation of production costs and assembling times.
Filmometric scale
Very unusual and particular scale, can be found on rare models by Universal Geneve and Heuer from the 50s.
Specifically speaking about the Universal Geneve Film-Compax, the double colored scales on the dial are used (…were used, may we say) to calculate how much photographic film was consumed in feet per minute. The red scale refers to 16mm film while the black refers to 35mm film, according to the era “typical” 24 photograms per second. Furthermore, the sub dial at three shows both films increments in feet per second.
All in one
To satisfy customers that may need to measure different phenomena on a single watch, it’s possible to find timepieces that showcase three scales on the same dial.
On the famous Patek Philippe ref. 5975 dial, apparently complicated to read, we find a telemetric scale, a 15-pulses pulsometric scale and a spiral tachymetric scale capable to track speeds as low as 20 km/h.
Translated by Lorenzo Spolaor (@itsdoc_oclock)
