How Long Is An Hour? Poem by Paul Hartal

There are science fiction stories
that describe other worlds, stars and
galaxies where inhabitants measure time
in a different way than us.

But you don’t have to read science fiction
for this. History shows that people
in the past already used different time
systems than we use today.

For example, in 1792,
during the French Revolution,
the authorities officially introduced
decimal time, which divided the day
into 10 hour. It also divided each hour
into 100 minutes and each minute
into 1oo seconds, as opposed
to our standard time,
which divides the day into 24 hours,
splits each hour into 60 minutes
and each minute into 60 seconds.
The length of one decimal hour
converted into our standard time
is two hours and 24 minutes.

Mind you, and quite astonishingly,
decimal time was also used in China,
as early as the first millennium BCE.
The ancient Chinese employed
clepsydras, or waterclocks, to divide
the day into 100 units, which they called
“ke”.

Actually, alongside with the decimal
system, the Chinese also used
a dozenal time keeping system
that divided the midnight- to- midnight
day into 12 double hours.
And during the Han Dynasty,
the philosopher Huan Tan,
who flourished about two thousand
years ago, wrote that he examined
clepsydrae and sundials
in order to compare their accuracy.

About a thousand years later,
in 976, the astronomer Zhang Sixun
replaced water with mercury to solve
the problem of freezing water
in clepsydrae in cold wheather.
Chinese engineers in this epoch
constructed marvelously sophisticated
mechanisms, such as Su Song’s
astronomical clock tower. Su Song was
an 11th century polymath, whose
astronomical clock tower comprised of
a clepsydra tank, waterwheel,
pendulum escapement wheel gear,
chain drive to power an armillary sphere
and 113 striking clock jacks
to sound the hours on a gong.