# What is a chronograph? How to read and use the tachymeter and other functions on a chronograph watch

Watches are cultural heritage filled with human wisdom and history, and are also works of art, but we must not forget that above all else, they are precision instruments.

In this article, we will explain how to use a chronograph and the names of its parts.

## A chronograph is a device that packs various measurement functions into one watch.

The word chronograph is a combination of the Latin words "chrono" (time) and "graph" (measurement).

The chronograph is the most familiar type of complicated watch, and its operation is similar to that of a stopwatch.

To put it simply, it is a wristwatch with a stopwatch function that uses the clock's power source.

Now that we have a general idea of what a chronograph is, let's take a closer look.

The series of operations - start → stop → reset (returning the chronograph hands and totalizer hands to their positions before time was measured) - is performed using the push buttons above and below the crown.

The steps are explained below with images:

Now, I will explain it with images.

**Press the start button at the 2 o'clock position**

↓

**Press the stop button at the 2 o'clock position (measurement will stop)**

↓

**Press the reset button at 4 o'clock**

When you press the start button, the red needle in the image above will start moving.

(The position of the hands varies depending on the watch.)

Basically, you press the start button to start the measurement, and press the start button again to stop the measurement.

Pressing the reset button will reset it to the 0 o'clock position.

This is the stopwatch function.

Below is a video of it in action.

Depending on the model, all of these functions can be done with the operation of a single button (called a one-push chronograph, and in most cases these are antiques made 100 years ago).

The chronograph hand is set on the central axis, and the elapsed time is displayed on the sub-dial. The sub-dial is usually a 30-minute and 12-hour counter, so you can read the "hour, minute and second" when the watch is stopped.

## Check your role from the dial

From here on, it's easier to understand by looking at the actual watch face, so I will explain while looking at the image below.### 01. Start/Stop button

The chronograph start/stop button is located above the crown (at the 12 o'clock position).

Press once to start, press again to stop.

Check the accumulated time while the machine is stopped.

### 02. 30-minute counter

This counter displays the elapsed time up to 30 minutes. Some manufacturers also have 45-minute counters. The chronograph hand advances one notch for each revolution (each minute).

### 03. Reset button

When you press the stop button to stop the measurement, the elapsed time is displayed on the center axis and each chronograph. Pressing the reset button at the bottom of the crown (6 o'clock side) resets all of these hands at once.

### 04. Chronograph hands

It is set on the same central axis as the hour and minute hands. It has a sharp tip and is easy to see with its red and orange color scheme. It starts moving as soon as you press the start button, and can record down to the second.

### 05. Small second

This is a small second hand displayed on the subdial. This is a normal second hand that is not related to the chronograph mechanism, so it is safe to say that it is unnecessary. However, as a rule, it is equipped to show that the watch is running. As an exception, there are models that are not equipped with it.

### 06. 12-hour counter

This counter displays the elapsed time up to 12 hours. The 12-hour counter advances one notch every time the 30-minute counter completes one revolution (30 minutes have elapsed). It is usually located at the 9 o'clock position, but some models only have a small second and a 30-minute counter and do not have one.

### 07. Rotating slide rule

A slide rule is printed on the rotatable bezel, and by matching this with the numbers on the dial, you can calculate flying (driving) speed and perform calculations such as multiplication and division.

This concludes the basics of how to use a chronograph watch and its uses.

The content from here on is advanced, so if you're interested, just read on.

From here on, we will explain about chronograph watches that have a function called a tachymeter.

##

**How to use a tachymeter on a chronograph watch**

A chronograph is just a stopwatch and is easy to use.

Now let's move on to explaining how to use the tachymeter.

##

How to use the tachymeter in a chronograph mechanism

First, before we explain the tachymeter, you need to know where it is located.

In the image above, it is the part with the small numbers (meters) around the dial.

Now that you understand that the tachymeter is a meter that surrounds the outer edge of the dial,

Let's keep reading.

Using a tachymeter requires a bit of math, but once you understand how to use it, you can measure all sorts of things, including speed, distance traveled, and even fuel consumption (you'll need a special ruler-slide tachymeter bezel to measure fuel consumption).

A tachymeter is a scale found around the bezel of a watch, or on the outer edge of the main face of a watch.

This scale consists of the following formula:

Tachymeter scale value = 3600 (number of seconds in an hour) / number of elapsed seconds

This scale allows you to convert elapsed time (in seconds) to speed (in hours).

Most tachymeter scales can be used to measure elapsed times between 7.2 seconds and 60 seconds and are only valid within that range of times.

Please note that this Speedmaster's scale starts at 500, at the 7.2 second position.

So, if you want to measure times shorter than 7.2 seconds, the tachymeter is of no use.

You can also use a tachymeter to measure the speed of something that takes more than 60 seconds,

You need to do a little mathematical calculation.

Also, keep in mind that a tachymeter can only measure distances that are known precisely.

With a little math, it's possible to measure the speed of an object traveling a distance that is greater or less than a given length.

Let's look at a few different scenarios and see how a tachymeter can be used to measure speed and distance.

## **How to Measure Speed Using a Tachometer**

To accurately measure an object's speed using a tachymeter, you need to know the distance between where you want the measurement to begin and end.

Let's say you are at a race track and the distance between corners 1 and 2 on the track is 1 mile (1.6 km).

Knowing the distance from corner 1 to corner 2, you can measure the average speed of the car.

As soon as the car has passed the first corner, press the start button on your chronograph.

Stop measuring when the car reaches the second corner.

According to the chronograph, it takes the car 40 seconds to move from corner 1 to corner 2.

If you look at the tachymeter scale on the bezel, the 40 second markings are aligned with the 91 markings on the tachymeter.

This indicates that the car's average speed as it moved from corner 1 to corner 2 was 91 miles per hour (146.45 km/h).

A tachymeter can be used to determine units of measurement other than miles, such as the international unit of distance, kilometers.

For example, imagine you are on a race track made up of kilometers.

You know that the distance from corner 1 to corner 2 is exactly one kilometre.

As soon as the car has passed the first corner, press the start button on your chronograph.

Stop measuring when the car reaches the second corner.

According to the chronograph, it takes the car 22 seconds to go from corner 1 to corner 2.

Since 22 seconds is directly on the 180 mark on the tachymeter, the car's average speed as it moves from corner 1 to corner 2 is 180 kilometers per hour.

If you want to measure the elapsed time over distances shorter than a mile or kilometer, you'll need to do a little math to find your average speed.

Start the chronograph when the car crosses the start/finish line and stop it once the car has completed one complete lap.

Let's say it takes 16 seconds to complete one quarter mile (400m).

16 seconds is on the 225 mark on the tachymeter scale.

However, the track is only a quarter mile (400 m), so the car cannot go 225 miles in an hour.

To get an accurate average speed, you need to remember that the track is only a quarter mile (400 m).

Then we calculate it out to be 1/4 of 225, which is 56.25.

Then we can determine that the car's average speed is 56 miles per hour (90 km/h).

So what if you want to measure something that takes longer than 60 seconds?

Remember that a tachymeter has a fixed scale and can only measure times to one minute.

However, with a little math, we can calculate your average speed over a longer period of time.

Let's say you're watching a mile horse race and you want to know the average speed of the winning horse.

Let's say the winning horse runs a mile in 94 seconds.

94 seconds is too long to measure on a tachymeter.

So let's look at the winning horse's speed in half a mile.

We can estimate that it took the horse 47 seconds to run a half mile.

(94 seconds ÷ 2 = 47 seconds)

47 seconds is in the range that can be measured on a tachymeter, and it lies on the 75 mark on the scale.

To find your speed, divide 75 miles per hour by 2 to get a speed of 37.5 miles per hour.

In addition to measuring the speed of a car, person, or horse, a tachymeter can also be used to measure how many of a product can be produced in one hour.

For example, if a watch manufacturer wants to know how many watches they can produce in one hour, they can use a chronograph to measure how many seconds it takes to complete one watch from the start to the end.

Thanks to our production machines, it only takes 55 seconds to produce one watch.

If you look at the tachymeter scale, 55 lies directly above 65.

This tells us that a watch manufacturer can produce 65 watches per hour.

## **How to Measure Distance with a Tachymeter**

In addition to finding the speed of an object, you can also use the tachymeter to find the distance traveled.

To find the distance traveled, you first need to know the speed at which it is moving.

And the speed of movement must be constant.

Let's say you're driving on the highway at 75 miles per hour.

Start the chronograph second hand.

When the second hand reaches 75 on the tachymeter, it has traveled one mile.

Again, in order to use a tachymeter to find distance, your speed must remain constant throughout the measurement.

Learning to use your chronograph dial watch is not that difficult.

And once you understand how to use a chronograph, you can take advantage of its functions in addition to the design of your watch.