180 YEARS OF

Pocket chronograph
from 1955 with splitseconds
hand-wind
Cal. 18.89 (diameter
= 18 lignes). Production
of this movement
began in 1905.
from 12 to 240 kilometers per hour. Another special
track design was calibrated to a distance of 100 meters to
accurately measure slower speeds.
THINNER AND FLATTER
When Longines introduced its Cal. 19.73 to the market,
customers were satised with a nished height of 9 mm,
but thinner pocketwatches had already become more
fashionable by the early 20 th century. is trend was unavoidable,
even in Saint-Imier. ere seemed to be no
reason to develop a completely new watch movement in
view of the excellent characteristics of the 19.73 caliber.
Its mechanism functioned perfectly and still oered
many potential design options. e engineers at
Longines used this to their advantage. By 1909 the height
had been reduced to a remarkable 1.6 mm, while providing
the same performance. e movement was renamed
19.73N (the “N” stood for “nouveau” or “new”). Tradi-
tional features included a variation with a jumping
30-minutes counter, while a concurrent version had an
hour totalizer geared toward newer trends. No wonder
this caliber was well suited for a wide variety of chronograph
types: pocketwatches with an open Lépine design,
elegant gold savonnettes with hunter cases, even
table clocks. Depending on the design of the dial, the
movement’s accuracy ranged between 1/5 and 1/10 of a
second.
e wide-ranging possibilities oered by the Cal.
19.73N became clear in the years aer 1909. A fundamental
modication of the oscillating system with a
smaller balance and more powerful hairspring made it
possible to record elapsed time precisely to the 1/100 of a
second. e central chronograph seconds hand circled
the dial in only three seconds. is high-tempo version
naturally drew down the available power reserve and reduced
it to a few hours. e lack of a time display made it
strictly a stopwatch rather than a chronograph. e
counter hand recorded time intervals of up to three minutes.
e system with a strong hairspring achieved
360,000 vph and required a modication of the chronograph
mechanism on the back of the movement. Two additional
levers controlled by the column wheel interacted
with the balance wheel for starting and stopping.
Moreover, there was also a special countdown version
with a frequency of ve hertz (36,000 vph) and a 15minute
totalizer. is stopwatch for bombardiers had a
chrono hand that moved in the normal clockwise direction.
Pressing the stop pusher on the right next to the
crown and another push on the crown itself activated an
intermediate wheel on the movement side that moved
the chronograph hand to the le, starting from its last
position.
LONGINES SPECIAL WatchTime | 41