Junghans J880.3 Manual De Instrucciones página 6

Tachymeter scale
The tachymeter scale indicates the average speed travelled over a
defined distance. The scale is based on a distance of one kilometre.
At the beginning of the distance start the timing procedure by pressing
the start-stop pusher (7). After one kilometre stop the timing procedure
by pressing the start-stop pusher again (7). The second hand displays
the average speed travelled on the scale.
For example: You are travelling as a PASSENGER in a car on the motor-
way. The reflector posts are at intervals of 50 m. You start the timing
procedure at the first reflector post and end the procedure at the 21st.
You have therefore covered a distance of one kilometre. The second
hand now shows you the average speed.
If you require 30 seconds for one kilometre, your average speed is
120 km/h.
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Telemeter scale
The telemeter scale is used to estimate the distance in kilometres
between a visible light, e.g. a flash of lightning, and hearing the accom-
panying noise.
Begin the timing procedure by operating the start-stop pusher (7) on
seeing the light, such as a flash of lightning. As soon as the sound of
thunder is audible, press the start-stop pusher again (7). You can now
read the distance of the storm in km on the telemeter scale.
An example: If the stop second hand on the telemeter scale stops at
the "2", then the storm is 2 km away. (2000 m: 334m/s = 5.99 seconds
= telemeter scale "2").
As light travels at the speed of light,
the time that the flash of lightning
requires to reach your location is ne -
gligible.
This is not the case with thunder, how-
ever, as this travels at the speed of
sound, i.e. at approximately 334 m/s
(at an air temperature of approximate-
ly 5°).
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