A tachymeter is a scale inscribed around the bezel of an analog watch, or sometimes printed on the dial, used to compute speed based on travel time or measure distance based on speed. It is particularly useful for measuring the speed of a moving object over a known distance or the distance covered at a constant speed.

How to Use a Tachymeter to Measure Speed:
1. Know the Distance: First, you need to know a fixed distance, typically one kilometer or one mile.
2. Start the Chronograph: As the moving object (e.g., a car) passes the starting point of your measured distance, start the chronograph function of your Jowissa watch. This is usually done by pressing the top pusher next to the crown.
3. Stop the Chronograph: Once the moving object reaches the end of the measured distance, stop the chronograph by pressing the same top pusher.
4. Read the Speed: Observe the position of the chronograph's central seconds hand on the tachymeter scale. The number on the tachymeter scale corresponding to the seconds hand's position indicates the speed in units per hour (kilometers per hour or miles per hour), based on the one-unit distance you measured.
- For example, if it took 30 seconds to travel one kilometer, the seconds hand would point to "120" on the tachymeter scale, indicating a speed of 120 kilometres per hour.

How to Use a Tachymeter to Measure Distance:
1. Know the Speed: You need to be traveling at a constant speed.
2. Start the Chronograph: As you begin timing, start the chronograph function of your Jowissa watch.
3. Time a Duration: Let the chronograph run for a specific amount of time, for example, 60 seconds.
4. Read the Distance: Note the number on the tachymeter scale corresponding to the position of the chronograph's central seconds hand. This number represents the distance traveled in the unit of speed you are using (kilometers or miles) during that specific time interval (e.g., per minute if you timed for 60 seconds).
- For example, if you are traveling at a constant speed and after 60 seconds the seconds hand points to "80" on the tachymeter scale, you have traveled 0.8 units of distance (kilometers or miles) in that minute.

The tachymeter function on your Jowissa chronograph is a testament to the precision and functionality inherent in our timepieces, blending traditional horological features with practical applications for everyday life.