The mechanical clock’s reliability was due to one of the most ingenious
inventions in clockdom: the “escapement.” Still in use, the escapement is a
pivoting lever that engages a toothed wheel at consistent intervals.
This regulated the “escape” of whatever is powering the
clock-descending weights or a spring, for example-in order to control the speed
at which gears and wheels turn, evenly metering out the power to measure the
time. It is the rocking motion of
the escapement mechanism that puts the tick tock into a clock.
As time ticked on, clocks sprouted fancy face pieces and dials.
At first, only an hour hand was deemed necessary.
But as society became more sophisticated, so did clocks, which gained
minute and second hands.
In the mid-1400s, European craftsmen discovered that coiled springs,
unwinding t the speed governed by an escapement, could move the hands on a
timepiece as effacingly as the weights of a tower clock.
This discovery made possible the first portable clocks, later reduced in
size to become watches.
But it was the development of the pendulum that clocks gained a once
undreamed of accuracy. In 1656,
Dutch astronomer and mathematician Christiaan Huygens created the first pendulum
clock-based on a principle Galileo had discovered: a pendulum swings at a
constant rate. Huygen’s clock was
off by less than a minute a day, a dramatic improvement over the 15 minutes or
so lost daily by earlier timepieces.
The longer the pendulum, the greater the accuracy, and long pendulums
became de rigueur. The longcase
clocks, commonly called grandfather clocks, often included a glass door through
which the clock owner’s guests could admire the pendulum.
“These were the high-tech clocks of the day, and definitely status
symbols,” notes Jonathan Betts.
As Betts walks us through clock-filled rooms at the observatory in
Greenwich, he relays his favorite clock story.
Not surprisingly, Betts’ tale is the story of time itself: the quest
for longitude.