Longines Calibre L699 Nstructions For Use page 9

Your Longines watch (see illustration I)
Your Longines watch is a precise and reliable timepiece designed for
daily use. Thanks to its ingenious combination of dials it differs from an
ordinary watch in three ways:
A The indications on the dial are designed in such a way that they show
the time (in hours, minutes and seconds) and the hour angle (in
degrees and minutes) simultaneously.
B The rotating central dial shows the seconds and it can be turned
using the crown in order to synchronize the watch with a radio time
signal.
C The bezel can be rotated to correct the equation of time (which varies
from one day to the next).
The space/time dial – How it functions
The overall design of the Lindbergh Hour Angle Watch takes into
account the fact that the Earth rotates through 360° in 24 hours,
through 180° in 12 hours, through 15° in one hour and through an arc
of 15' each minute. Consequently:
– The hour hand moves through 15° per hour; one rotation of the dial
(12 hours) equals the Earth's rotation through 180°.
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– The minute hand moves through 1° every 4', in other words 15° per
hour; each of these 15 degrees is subdivided into four arcs of 15'; all
these indications are engraved on the rotating bezel.
– One complete rotation of the central seconds hand equals a 15' arc;
the rotating central dial is divided into 60» and arcs of 15'.
Synchronizing your watch with a radio time signal
Pull out the crown to the intermediate position 2 and turn the central dial
until the seconds hand is on the «60/15» mark at the last pip of the time
signal.
Functions of the 3 positions of the crown (see illustration I)
1. Pushed in
Winding: The natural movement of your wrist will automatically wind
your Lindbergh Hour Angle Watch, which has a power reserve of 42
hours. It is only necessary to wind the watch manually if it has not been
worn for several days.
2. Intermediate position
The crown can be used to turn the central dial (in both directions).
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