L699 - The Lindbergh Hour Angle Watch - Longines L602 Manual

Hour hand
C
Seconds hand
A
minutes, seconds, hour
angle dial
The original Lindbergh Hour Angle Watch was designed by Charles
Lindbergh as a navigational aid for pilots. Used with a sextant and a
nautical almanac, this watch enables the wearer to quickly determine
the hour angle from Greenwich, in other words his or her longitude.
Thanks to its ingenious combination of dials, this time-piece differs
from an ordinary watch in three ways:
A The indications on the dial are designed in such a way that they
show simultaneously the time (in hours, minutes and seconds)
and the hour angle (in degrees and minutes of arc).
B The rotating central dial shows the seconds and it can be turned
using the crown in order to synchronise the watch with a time
signal.
C The bezel can be rotated to correct the equation of time (which
varies from one day to the next).
Book_I.indb 75
Automatic watches
Rotating bezel
Central rotating hours,
L699-Lindbergh
L699 – THE LINDBERGH HOUR ANGLE WATCH
Minute hand
3-position crown
1 2 3
D
Push-piece to open
the case-back
B
Central rotating
seconds dial
3-position crown
Adjusting the time and stop seconds
(See page 68)
Synchronising the watch with a time signal
In the intermediate position 2, the crown can be used to turn the
central dial (in either direction). Pull the crown out to the intermedi-
ate position 2 and turn the central dial so that the seconds hand
points to the "60/15" position on the last pip of the time signal.
Push the crown back in to position 1.
Push-piece  at 4 o'clock
This is for opening the case back, thus revealing the movement
through a protective sapphire glass.
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