The Clock of Flowing Time
Europa-Center, Berlin
The Hypnotic Effects of an E-Clepsydra
A conversation between two intelligent women
The Water Clock or Clepsydra
Quiz #480 Results
Bookmark and Share
Answer to Quiz #480- June 14, 2015
1.  What is the name of this kind of device?
2. What is the reading at the moment?
3.  What are two older ways of measuring the same thing?
1.  A water clock, or clepsydra.
2. 2:42 pm
3.  A sundial, a gnomon, a set of sticks.
Comments from Our Readers
At first I thought this must be a barometer.  That didnt pan out.  Then I tried to
identify the building.  That was another dead end.  Then I searched for spiral glass
liquid and wound up looking at a picture of some really awful earrings.  But
somewhere in that search the word timer showed up.  I looked at the picture
again.  How obvious.  It is a clock and the picture was taken about 2:42pm.  It
is daylight outside.  This clock is a water clock or clepsydra designed by Bernard
Gitton.  This particular clock is located in the central hall of the Souk Sharq
shopping center in Kuwait City, Kuwait.

Older ways of telling time:  The sundial and the merkhet

Video:  Bernard Gitton - Physics and Art

I would not want to be responsible for having to move one of those clocks.
Carol Gene Farrant
Thanks Colleen.  Have to say though that I had help with what it was called but
once found it to be a water clock soon found that image on the net.  The other two
answers to the questions weren’t too difficult.

These puzzles certainly help to keep the old brain ticking over!
Maggie Gould
Your stick in hole calendar reminds me of the cartoons where the prisoners mark
lines on the wall and then bi-sect the lines with another line to distinguish blocks of

Actually, sometimes the simple/crude methods work the best, but remembering is
key as there is a part that you have to play in the process and changing the stick
certainly can make all the difference.

I thought your question about distinguishing between AM and PM pertained to the
time clock itself not simply looking out a window. Sometimes, I think I read too
much into questions as I try to be too precise in responding.
Cindy Costigan
Thanks again, Fearless Leader!!!!!!!!!!! Great job as usual keeping the fuzz
between our ears active!

[The online animation] is amazing! Thanks again.
Grace Hertz and Mary Turner
I just remembered that weird scene in Cast Away where Tom Hanks is calculating
the date by counting sticks marked in a wall for the number of days in the island....

Pretty cool tool to explain recursiveness and conversion to binary. Never imagined
that the clock was actually digital.
Ida Sanchez
N.B. We were trying to figure out how to fit the 2^5 = 32 "beats" into a 60
second minute.  We came to the conclusion that the "beats" are not 1 second
long-  that the length is adjusted so that a beat is 60/32 seconds long. - Q Gen.

Congratulations to Our Winners!

Margaret Paxton                Ida Sanchez
Gus Marsh                Tony Knapp
Maggie Gould                Jim Kiser
Carol Farrant                Cindy Costigan
Jon Edens                Ellen Welker
Megan Neilsen

Grace Hertz and Mary Turner
The Fabulous Fletchers!
If you enjoy our quizzes, don't forget to order our books!
-- Start Quantcast tag -->
If you have a picture you'd like us to feature a picture in a future quiz, please
email it to us at If we use it, you will receive a free analysis of
your picture. You will also receive a free
Forensic Genealogy CD or a 10%
discount towards the purchase of the
Forensic Genealogy book.

How Ida and Tony Solved the Puzzle
I have to admit I almost gave up. I was lost between barometers and
thermometers, a combination of both and all other weather-related
devices. Then, plain and simple observation without any searches
brought the answer. I started thinking, what would need numbers
from 1 to 11 and also from 1 to 60...Duhhhhh

Funny thing is, I googled "fluid based clocks" and most of the
answers were about cleaning fluids for mechanic clocks, so I had to
take the "cleaning" out and I saw that the proper name was "water
clock". Searching specifically for it brought me to the Wikipedia page
that holds all the answers.

Ida Sanchez


I tried a different approach to this picture. I tried just looking at the
picture without looking at the questions.

When I saw this picture I was reminded of the quizzes which had
similar types of glass devices which measured pressure and
temperature. At first I just tried some general searches like "glassware
with blue liquid" which turned out to be too general. So I looked more
closely at the "numbers" and it dawned on me that it measured time
so it was a clock.

I searched for "blue liquid in glass clock" and saw a similar picture
from wikipedia. On going to wikipedia, I learned that it was a water
clock (or clepsydra) which had been developed by Bernard Gitton.
On searching images for "Bernard Gitton clock" I came upon the
above image which was located at This site
gave a very good description of how the clock worked. This
particular clock is the only water clock in the Gulf. It is located at the
Souk Sharq Mall in Kuwait City, Kuwait, and is an inflow water
clock. After finding this information I looked at the questions.

Tony Knapp
The Modern Water Clock
Click on thumbnail of water clock
to see an animated version
of how it works.

Clock will be initialized
by the clock on your computer.

I'm risking being tardy again in getting a properly set-out reply to you
for the latest wicked quiz.  I say "wicked" because it diverted me
earlier in the week from things I should have been doing.  Not
because of the questions you asked, but because of those you didn't.  
Working out what I was looking at (after initially being flummoxed)
was not the problem.  The problem was understanding how it
worked.  "What is the go of it?" (to quote James Clerk Maxwell) is
what sends us to physics in the first place, n'est-ce pas?

Just in case you haven't already happened upon it, those answers are


along with a really cool animation at

Be sure to "cliquez ici".   The result, in my experience, locks to the
time on your computer's clock and continues to sit there as an
alternative time-keeper.

So we don't actually have to go to Kuwait (or Indianapolis, Berlin, or
...) to see Gitton's extraordinary work in action.

More anon,

Megan Neilsen


Darn you Megan!

I've been sitting here totally hypnotized by this animation of the water
clock.  Totally fascinating!  

I've been watching it on my phone and it seems to be running too
slow.  It's probably because of the refresh rate of the phone.  It
started out at 9:58 - which was the correct time- but it didn't flip over
to 10 am until it was really 10:05 am.  I am going to look at it on my
laptop.  Maybe it will stay in synch.  I'd actually like to use it as the
clock for my desktop.  If the water clock runs smoothly on my
computer, I will use it to make sure my computer clock is running
correctly.  :-)

- Q. Gen.


Same reaction as I had  - Darn you Colleen!  OK, seems that it's me
who found the hypnotic animation, but it's your fault in the first
place, you wicked woman.

I've had it running, on and off, over the last week.  On my desktop
box with big grunt it keeps pretty good time.  I think it depends more
on processor resources than on refresh rate.  With an independent
processor it would be a great everyday clock. And yes, great minds
... I've contemplated that too.

It is indeed fascinating but I'm presently giving it a rest.  He who has
his head in nonlinear dynamic systems most waking hours walked by
remarking, "Are you still looking at that clock!"  Now that's a great
case of the pot calling the kettle black, don't you think?

Enough!  Except to say it would be nice if I'd spelt clepsydra
correctly in what I sent earlier ...

A water clock or clepsydra (Greek
κλεψύδρα from κλέπτειν kleptein, 'to
steal'; ὕδωρ hydor, 'water') is any
timepiece in which time is measured by
the regulated flow of liquid into (inflow
type) or out from (outflow type) a vessel
where the amount is then measured.

Water clocks, along with sundials, are
likely to be the oldest time-measuring
instruments, with the only exceptions
being the vertical gnomon and the day-
counting tally stick. Where and when
they were first invented is not known,
and given their great antiquity it may
never be. The bowl-shaped outflow is the
simplest form of a water clock and is
known to have existed in Babylon and in
Egypt around the 16th century BC. Other
regions of the world, including India and
China, also have early evidence of water
clocks, but the earliest dates are less
certain. Some authors, however, claim
that water clocks appeared in China as
early as 4000 BC.

Some modern timepieces are called
"water clocks" but work differently from
the ancient ones. Their timekeeping is
governed by a pendulum, but they use
water for other purposes, such as
providing the power needed to drive the
clock by using a water wheel or
something similar, or by having water in
their displays.

The Greeks and Romans advanced water
clock design to include the inflow
clepsydra with an early feedback system,
gearing, and escapement mechanism,
which were connected to fanciful
automata and resulted in improved
accuracy. Further advances were made
in Byzantium, Syria and Mesopotamia,
where increasingly accurate water clocks
incorporated complex segmental and
epicyclic gearing, water wheels, and
programmability, advances which
eventually made their way to Europe.
Independently, the Chinese developed
their own advanced water clocks,
incorporating gears, escapement
mechanisms, and water wheels, passing
their ideas on to Korea and Japan.

Some water clock designs were
developed independently and some
knowledge was transferred through the
spread of trade. These early water clocks
were calibrated with a sundial. While
never reaching a level of accuracy
Only a few modern water clocks exist today. In 1979, French scientist Bernard Gitton
began creating his Time-Flow Clocks, which are a modern-day approach to the
historical version. His unique glass tube designs can be found in over 30 locations
throughout the world, including one at Europa-Center's
The Clock of Flowing Time in
Berlin, Centre Commercial Milenis in Guadeloupe, the
Giant Water Clock at The
Children's Museum of Indianapolis in Indianapolis, Indiana, and the Shopping Iguatemi
in São Paulo and Porto Alegre, Brazil.

Gitton's design relies on gravity powering multiple siphons in same principle as the
Pythagorean cup; for example, after the water level in the minute or hour display tubes
is reached, an overflow tube starts to act as a siphon and thus empties the display tube.
Actual time keeping is done by a calibrated pendulum powered by a water stream piped
from the clock's reservoir. The pendulum has a carefully constructed container
attached to it; this measures the water that is then poured into the display system.

There are other modern designs of water clocks, including the
Royal Gorge water
clock in Colorado, the Woodgrove Mall in Nanaimo, British Columbia, in the
Abbotsford Airport (formerly at Sevenoaks Shopping Centre) in Abbotsford, British
Columbia, and the
Hornsby Water Clock in Sydney, Australia.
Noon time Time-Flow Clock by Bernard Gitton, Rødovre Centrum, DK

Marking the grand entrance to the Royal Gorge
Bridge and Park, this unique time-keeping
creation is one of only three in the world, and
the only one in Colorado. Its splashing water
cascades from bucket to bucket, keeping track
of every minute of the day.
Royal Gorge Water Clock
Canon, Colorado

It is a combination of three water-powered
clocks – a 4th-century BC Greek clepsydra, an
11th-century Chinese water wheel clock and a
17th-century Swiss pendulum clock – plus a 17-
note bronze carillon to ring the hour based on a
250-year-old design found in an old English
church. The whole assembly is mounted on a
floating pontoon that rotates every 12 hours
giving a fourth time indicator as a pointer
sweeps past Roman numerals placed in the
water around the fountain's perimeter.
Hornsby Water Clock
Florence St., Hornsby, NSW Australia
For an explanation of how Bernard Gitton's Water Clocks work, see

Bernard Gitton's Liquid Science
By David M. MacMillan
With "buckets" of help from Daryl Bender
The Accuracy of Water Clocks
The rate at which a fluid passes through an orifice depends, other things being equal,
on the viscosity of the fluid. Approximately, the flow rate is inversely proportional to
the viscosity. The viscosity depends on the temperature. Liquids generally become less
viscous as the temperature increases. The reverse is true of gases. In the case of water,
the viscosity varies by a factor of about seven between zero and 100 degrees Celsius.

Thus, a water clock would run about seven times faster at 100 °C than at 0 °C. Water
is about 25 percent more viscous at 20 °C than at 30 °C, and a variation in temperature
of one degree Celsius, in this "room temperature" range, produces a change of viscosity
of about two percent. Therefore, a water clock that keeps good time at some given
temperature would gain or lose about half an hour per day if it were one degree Celsius
warmer or cooler.

To make it keep time within one minute per day would require its temperature to be
controlled within 1⁄30°C (about 1⁄17° Fahrenheit). There is no evidence that this was
done in antiquity, so ancient water clocks (unlike the modern pendulum-controlled one
described above) cannot have been reliably accurate by modern standards.
Ancient Persian Water Clock
A Water Clock in the Forbidden City
Elephant Water Clock in Dubai
comparable to today's standards of timekeeping, the water clock was the most accurate
and commonly used timekeeping device for millennia, until it was replaced by more
accurate pendulum clocks in 17th-century Europe.