180 YEARS OF

1977
Response to
the Quartz
Crisis
CALIBER L990
It took courage to launch a new
automatic caliber in 1977. Aer two
years of research and development
work, Longines presented the ‘E’
caliber family, which was later renamed
L990. Just 2.95 millimeters
thick, it was the world’s slimmest
movement with two barrels and automatic
winding via a central rotor.
Its most notable characteristic was a
pair of serially arranged barrels that
had made their debut in automatic
Caliber L890 in 1975. e energy
and rotational speeds of the two
barrels combined to produce a 44hour
power reserve. e comparatively
quickly turning mainsprings
had lower torques: this signicantly
reduced the force exerted on the
gear train while at the same time
achieving superior performance.
84 | WatchTime LONGINES SPECIAL
is solution made it possible to
lower the transmission ratio of the
train between the rotor and the barrels,
while also enabling the engineers
to eliminate one gear and to
reduce both the weight and the
thickness of the ball-borne rotor.
anks to the simplicity of its architecture,
the entire self-winding
assembly could be positioned below
the barrel bridge as an integral
component of the movement. ere
were four caliber versions: L990
with central seconds and date display;
L992 with central seconds but
without a date display; L993 with
date display but without a secondhand;
and L994 with hands only for
hours and minutes. Breguet, which
like Longines is part of the Swatch
Group, now owns rights of this caliber,
to which it has given a silicon
escapement and the name “591A.”
1979
Paper-in
GOLDEN LEAF
Japanese watch companies seized the
lead from the Swiss in the development
of thin electronic movements in
1978. Longines, a pioneer in the world
of quartz watches, refused to take this
lying down, so the brand joined with
its sister company ETA and other
members of the Allgemeine Schweizerische
Uhren AG (ASUAG) to
launch an ambitious project called
“Delirium.” The goal was not only to
break records, but also to overcome
the severe crisis that faced
the Swiss watch industry
at the time.
Longines’s management
celebrated a
spectacular success
on January 12,
1979, when it introduced
the world’s
slimmest quartz
wristwatch with an
analog time display
and an overall height
of just 1.98 millimeters.
The brand launched
this timepiece under the
appealing name, Golden
Leaf. The technicians
who created its movement,
Caliber L795.2, had radically
departed from conventional
principles of construction. The
case’s back doubled as its base
plate. After assembling the
movement and inserting the
hands, watchmakers needed only
to install the bezel and the crystal
above the dial. The hands could be
reset by pressing a little button in the
back of the slender, golden case.
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