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76
L699 – THE LINDBERGH HOUR ANGLE WATCH Automatic watches
How to use your The Lindbergh Hour Angle Watch
Having synchronised your watch with a time signal. As an example
when you check it your watch shows 4 hours, 37 minutes and
12 seconds. The equation of time for the day in question is minus
4 minutes and 50 seconds.
Therefore move the marker situated at “15” on the bezel 4 gradua-
tions to the left. These graduations represent the minutes engraved
around the case.
Your data are as follows:
Seconds hand (centre dial) 3’
Minute hand (bezel) 10° 15’
Hour hand (main dial) 60°
As you have only turned the bezel by 4 minutes,
you still have to take into account the 50 seconds
(the equation of time being 4 minutes and
50seconds for the day in question).
On the central dial, the 50 is opposite 12½ . /. 12½’
Greenwich hour angle of the sun
(your longitude)
70° 5½’
The space/time dial and how it works
The design of the whole of The Lindbergh Hour Angle Watch takes
into account the fact that the Earth revolves through 360° in 24hours,
through 180° in 12 hours, through 15° in 1 hour and through 15’
of arc in 1 minute.
Consequently:
The hour hand indicates 15° per hour. One complete circle of the
dial (12 hours) is equivalent to 180°.
The minute hand indicates 1° per 4’, in other words 15° per hour.
Each of the 15° is subdivided into four sectors of 15’ of arc. All
these indications are engraved on the rotating bezel.
One complete circle of the centre seconds is equivalent to 15’ of arc.
The rotating central dial is divided into 60’’ and 15’ of arc.
Book_I.indb 76 13.08.19 10:56
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