Chronometer vs chronograph watches

“Superlative Chronometer Officially Certified” it’s said. What does that mean and what’s the difference with a chronograph watch? Chronometer vs chronograph : fight !

Let’s start with the Chronograph:
The Chronograph is a type of watch with the function to measure time periods. In Greek, “Chronos” means time while “graph” means writing. Therefore it’s literally “writing down the time”.

Rieussec Chronographe

By 1921, the very first version of a chronograph was indeed “writing” on two rotating disc of paper (pic above). Ink pens attached to hands were drawing circle! The chronograph concept was born. Through this method, people were able to see time periods thanks to the lengths of the lines that were drawn. This invention was made by Nicolas Rieussec upon request of French King Louis XVIII to time horse races. Since then Nicolas Rieussec has been considered as the inventor of the chronograph concept. The following year, he patented the chronograph without ink, instead using hands on a dial to display time.

Later, chronographs were housed in pocket watches and finally in wristwatches. The first chronographs as we know them today were using a single pusher. Those watches were able to record only one interval of time, as the third push on the button was resetting the chronograph (first push for starting the measure; second one for stopping the measure). It’s in 1915 that Gaston Breitling patented the two-pusher chronograph, which allows stopping a time period and then continuing it. The second pusher was made to separate the reset function.

To sum up, a chronograph is a stopwatch function. On a chronograph watch, you will usually find two pushers on both sides of the crown and two sub dials to count minutes and hours of the time recorded (as on the Breguet above / the last sub dial at 3 o’clock is for the small seconds).

logo_cosc

On the other hand, a Chronometer watch, is actually a watch with a certification of accuracy. This word only relates to the COSC certification. This means that the watch’s calibre has passed specific laboratory tests ran by the independent observatory COSC (Contrôle Officiel Suisse des Chronomètres). All kind of watches can be certified “chronometer” as long as they were controlled and certified by the organization.

To be a chronometer, the calibre has to give a daily precision of -4/+6 per day to the watch. We have also written an article where you will learn everything on watch certifications.

This is how a chronograph watch can also be a chronometer ! -> you get a chronograph with a better precision. This is indeed the case for the Rolex Daytona! However, a chronometer watch is not necessarily a chronograph!

 

One last thing! Do you know who is Louis Moinet and what is a chronoscope?!
Two years ago in 2013, the Swiss brand Louis Moinet revealed that the first ever device measuring time was actually invented in 1816 by the French watchmaker Louis Moinet. This stopwatch is known as the Compteur de Tierces (photo below) and was able to measure intervals up to 1/60 of a second. As Rieussec has received credit for inventing the first chronograph, Louis Moinet’s invention has been referred to the first chronoscope (which doesn’t required writing down time intervals – scope meaning watching time). Louis Moinet created this stopwatch for astronomical calculations purposes.

louis-moinet-compteur-de-tierces-02

See you soon for a next article to share our love for mechanical watches !