Tachymeter
Scale on the watch used to measure speed in km/h. Start the chronograph, walk or
run exactly 1 km from your point of departure. Look at the dial of your watch, the se-
conds-hand on the “tachymeter scale” indicates your speed in km/h for the kilometer
just traveled.
Telemeter
Scale to measure the distance between the observer and a visible, then audible phe-
nomena. The graduated dial enables distances to be read off at the speed of sound
(343m/s). For example, to calculate the distance of a thunderstorm, start the chro-
nograph when you see the lightning; then stop the seconds-hand when you hear the
thunder. Look at your watch dial, the seconds-hand on the “telemeter” scale indicates
the distance separating you (X) from the position of the lightning.
Moon phases
Watches with a moon-phase complication display the cycles of the moon on their dial
(first quarter, full moon…). Moon phases are generally displayed using a moving disk
which makes one rotation every lunar month (29 and a half days).
Tourbillon
This function was designed by Abraham-Louis Breguet to compensate for rate dis-
crepancies caused by the earth’s gravity. A tourbillon involves a moving carriage which
holds the watch’s regulating organ (balance and spring) and its escapement. The es-
cape wheel pinion turns around the fixed seconds wheel. The cage makes one turn/
minute; by turning it compensates for rate discrepancies occurring when the watch is
kept vertical. The rotation of the entire body around the carriage axis (1 turn/minute)
compensates, therefore erasing the effects caused by friction as well as those caused
by imperfectly balanced parts or by gravity when the watch is in a vertical position.
A mechanical watch has a power reserve of about 40 hours. We recommend you
wind it each day.
SELF-WINDING MECHANICAL WATCH
A watch with a self-winding mechanical movement is automatically wound as its wearer
performs certain everyday movements.
Because of this, the watchband must be correctly fitted to the wearer’s wrist. If the wat-
chband is too loose, the watch may lose some of its autonomy. To keep your watch opti-
mally wound, wear it every day.
Before wearing your watch, you must wind it manually by turning the crown clockwise
approximately 20 turns. After wearing your watch for several hours, depending on your
activity level, the watch will be perfectly wound.
When not worn and completely wound, your watch has a power reserve of approximately
40 hours.
IB. Principal watch functions and complications
Power reserve
A hand indicates how much of the watch’s power supply remains (for both self-winding
and hand-wound watches).
Dual Time Function
A watch equipped with a dual time zone complication is able to indicate a “2nd time
zone”. Most often, this second time can be read using a central hand located in a dial
graduated from 1 to 24 or it may be indicated in an aperture.
Chronograph
A watch which can measure time elapsed. A chronograph model generally also
contains a central seconds-hand for counting seconds, a counter for totalling minutes
and another for totalling hours.
76
English
