BALL Watch BMW Owner's Manual - page 10
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ENGLISH
• Date Setting: Unscrew the crown and pull it out to position [1]. Turn
the crown counter-clockwise to set date. To prevent damage to the
date-switching mechanism, we advise not to manually reset the date
between 9pm and 3am. Ensure that the date change takes place at
midnight and not at noon.
• Set the time of the second time zone: Turn the crown clockwise
until the correct time zone appears on the dial. Turn the GMT hand
in one-hour increments to prevent wear on the movement.
• Set the local time: In position [2], turn the crown forwards or
backwards.
GMT
See instructions for “Automatic Watch”
above, with the following changes.
Chronometer Certificate
A Chronometer is an extremely accurate watch. It takes its name
from the Greek words chronos + metron meaning “to measure
time”. A BALL chronometer is a highly accurate, mechanical watch
whose precision has been tested and verified by The Official
Swiss Chronometer Testing Institute (Contrôle Officiel Suisse des
Chronomètres, or COSC, in French).
Before issuing the certificate, the COSC conducts elaborate precision
tests on each BALL movement using cameras and computers and
analyzes the data. The COSC performs seven different tests. Failure
to meet the minimum standard in any one of the tests means that
a movement is rejected. Here is a brief summary of the testing
procedures:
※
Test 1
Mean daily rate: After 10 days of tests, the mean daily rate of the
movement must be within the range of -4 to +6 seconds per day.
The COSC determines the mean daily rate by subtracting the time
indicated by the movement 24 hours earlier from the time indicated
on the day of observation.
※
Test 2
Mean variation in rates: The COSC observes the movement rate in
five different positions (two horizontal, three vertical) each day over
10 days for a total of 50 rates. The mean variation in rates can’t be
more than 2 seconds.
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