English
Specific section
22
TELEMETER FUNCTION
The telemeter scale measures the distance of a
phenomenon which is first visible and then audi-
ble. The chronograph hand is released at the
instant the phenomenon is seen and stopped
when the sound is heard. Its position on the
scale shows, at a glance, the distance, in kilo-
meters, separating the phenomenon from the
observer.
The telemeter is so graduated that the sound
travels at a speed of 330.7 meters (approx.
1084.97 feet) / second, that is 1 km (approx.
0.62137 miles) in 3 seconds.
If we want to know at which distance a thunder
storm is taking place, for example, the chrono-
graph hand is activated as soon as the flash of
lightening is visible. When the crash of thunder
is audible, the chronograph hand is stopped. The
hand indicates on the telemeter scale the
distance between the observer and where the
phenomenon has taken place.
English Chrono VSA
13.10.2009
15:09
Page 22
