For a template to use to build a
paper replica of the Houfeng Didong Yi
What Happens When You Get Hooked on a Quiz
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.
If you enjoy our quizzes, don't forget to order our books!
Quiz #359 Results
Bookmark and Share

1.  To detect earthquakes in ancient China
2.  Seismograph
3. Tell the direction of the quake, find the epicenter,
alert people by cellphone,
generate maps on the internet, and lots more!
Answers to Quiz #359
July 8, 2012
1. What was the purpose of this ancient invention?
2.  What is the name of the modern version?
3.  Name something that the modern version can do
that the ancient version could not.
How Christine Solved the Puzzle
I knew right away it was Chinese because of the curly noses design
of the dragons, but then I wondered what it actually did. My first
guess it was something to do with tea, like a samovar. You put the
tea in, the clapper thing stirred it around and then when it was ready
the balls dropped into the frog and the tea could be poured out of the
dragon's mouth. Then I thought, well probably not, as they have
those other teapots that they use.

Then I thought, frog feeder, its a bell timer of sorts! The weight of
the balls slowly moved them downwards until they dropped, and then
the clapper moved back and forth and the bell rang. It signaled the
time you should feed the frogs, or do what ever else is important.
But, I wasn't happy with that either. Did it use steam? Was it
something that used steam to fuse or unfuse or power things?  

So I googled "drawing of ancient Chinese steamer" and clicked on
wikipedia. There was a very fascinating article on all of the ancient
chinese inventions including a photo of a seismometer, "A replica of
Zhang Heng's (78–139 AD)seismometer that employed a pendulum
sensitive to inertia of ground tremors; while placed in Luoyang in
133, it detected anearthquake 400 to 500 km (250 to 310 mi) away in
Gansu". Its a seismometer!

The modern seismometers have the ability to precisely find the fault
that caused the earthquake, they be linked together to create a picture
of underground features and then used to find water and oil.

Christine Walker
Comments from Our Readers
I used to be the publications coordinator for the Seismological Society of America,
where I edited one of the journals.  The cover image of one issue was a photograph of
one of a earthquake detector. The accompanying article talked about how some of the
modern earthquake alert systems have electronic notifications.  I knew what this was
as soon as I looked at it.

Janice Sellers

Why that is a Houfeng Didong Yi, of course!   I certainly wish I had one of those here
in sunny FL even though we don't experience many quakes here; we do have some
very interesting weather phenomena...hurricanes, tornadoes, fantastic lightning shows.  
I believe the original Seismoscope invented by Zhang Heng in 132 AD has been lost.  
Too bad; it was an amazing invention for that time period.  It certainly looks a lot nicer
than the current seismographs that we use today.  Sure, the new ones (and even the
early ones such as that invented by Schiantarelli in 1783) can now measure the
magnitude of a quake; but they were in no way as beautiful as the original.  Different
scales to measure the magnitude have been developed since the 1780s right up to the
Richter scale that we use now.

Dennis Brann

We first considered timing devices of timekeepers. But that did not fit. Then ancient
dispensing or vending devices.

Then we started wondering about measurement instruments for one time events and
John came up with seismographs. Research led me to this chinese instrument which is
a really beautiful work of art.

Marcelle Comeau and John Berkey

I am glad you like doing the quizzes. To bad the pay is minimal. On the other hand, you
do get exposed  to a lot of information you may not have gotten otherwise. I assume
the weekly quiz master tells you what to search for.

Arthur Hartwell

At first I thought it was some sort of garden water feature, like a deer chaser.  Then I
thought it might be some kind of timer.  But I couldn't f1igure out what would make
the stick inside the container move.  Still thinking water, I googled 'dragon dropping
water into frog'.

It's got to be a seismoscope, used to detect the general direction of an earthquake.  The
earliest known one developed by Chang Heng around AD 132.  Its descendent is the
seismograph.  The seismograph can detect the magnitude of the earthquake which the
seismoscope could not do.

Several of your quizzes have been timely.  If there is something you know that you
haven't told us, 'fess up now!

Carol Farrant

this was easy in that i merely googled "dropping a ball into a frog's mouth" and got the
whole answer!   but what a cool instrument for the Chinese to have used. So glad I
learned about this one.

Debbie Johnson

Very interesting to me.  Thank you Colleen.

Judy Bradley

Neat quiz!  At first, I thought it was some sort of a lean-detector/Level that would be
used on a boat.

Alex Prociv

[Someone thought it was a] lawn sprinkler?!   That cracked me up!  Too funny.

I got it on the first try as well.  I tried the obvious and googled - Chinese dragons
dropping balls frogs - and it was top of the list.  Another interesting subject from
Chinese history...courtesy of the weekly quiz!

Shirley (still chuckling about the lawn sprinkler...)

Wow! I have never heard of the Heng's Dragon Jar before today. It goes to show how
intelligent people were over 2000 years ago.

Sharon Martin

Colleen, I got this on my first try by typing in "ancient invention, dragon dropping ball
into mouth of frog". How's that for "brilliant" searching!  I am on a roll here!

Maureen O'Connor

1. Either laundry, water, tea, coffee, or pearl cleansing. And I am sure it is NOT a
device for cleaning golf balls!

2. Could not identify using various Google searches and, in desperation, Tin Eye.

3. The vessel appears to have a removable lid and the lion's mouth can open or close to
drop the spherical object into the frog mouth. I suspect it is of Chinese or, less likely,
Japanese origin. As I don't know its purpose, all I can suggest is that the modern
version is more clearly labelled with an instruction manual available on the internet for
download at no additional cost.

Richard Wakeham

I got it by Google with phrase "hit stick ball drops from bird to frog's mouth" -- can't
believe it worked to find the answer that is.  I thought the right side looked like a bird
kicking the ball.  I see now that the left side is a dragon.  What a clever device.

Judy Pfaff

This was a "Single-Google solution" - 'urn device drop balls' found the answer.

Peter Norton

I used the words: ancient=invention ball frog jar lever to arrive at contest answers.

Mike Dalton

I used the term "finder" intentionally, because the device was supposed to indicate the
direction of the earthquake, not just that an earthquake had occurred. (Presumably, if
the 'quake was big enough to drop the balls, it was probably big enough to be felt by
people, so they already knew it had occurred. What the ruler needed to know was
where the damage was heaviest, so that aid could be sent in the right direction, I think.)

I had the advantage of running across this device while researching old Chinese clocks,
back when working on the time brochure. So I didn't waste time googling odd phrases.
Quiz #358, July 1, 2012, Wait a Second!).

Collier Smith
Congratulations to Our Winners

Arthur Hartwell                Christine Walker
Janice Kent-MacKenzie         Carol Farrant       
Debbie Johnson                Judy Bradley
Alex Prociv                John Thatcher
Leon Stuckenschmidt                Daniel Jolley                Jillian Dart
Dennis Brann                Margaret Paxton
Gus Marsh                Gary Sterne
Claudio Trapote                Sharon Martin
Frank Nollette                Maureen O'Connor
Donna Jolley                Ben Hollister
Milene Rawlinson                Nicole Blank                Janice Sellers
Janice Sellers                Angel Esparza
Bob Witherspoon                Judy Pfaff
Anne Marie Laberge                Peter Norton
Collier Smith                Shirley Hamblin
Mike Dalton                Talea Jurrens
Marcelle Comeau and John Berkey
Hi Colleen

China is affected by both the Ring of Fire and the Alpide Belt, so accurate
knowledge of earthquakes would have greatly assisted Chinese Emperors to
effectively control and manage their empires.   

All this has lead me this am on a scientific exploration!

It has been amazing to find links between the last two quizzes!


Janice Kent-MacKenzie
The First Seismograph
When critics accuse the Chinese of stealing
technology from the West, consider that China
was the most technologically advanced nation
in the world for more than two thousand years
until the middle of the 19th century.

One example of China’s technological abilities
was when the first seismograph was invented
in 132 AD.

When Zhang Heng‘s device measured an
earthquake in 134 AD, he predicted the location.

Han Ministers did not believe the scientist.
Then a courier arrived and reported that an
earthquake had taken place where Zhang said it

In 1951, Chinese scientists from China’s
National Museum worked on recreating Zhang
Heng’s seismograph. Since there was a limited
Interesting Tie-In
The Leap Second (
Quiz #358) vs Earthquakes (Quiz #359)
Submitted by Janice Kent-MacKenzie
The Earth's rotation is slowing but at a much slower rate than 1 leap second every so
many years. The length of time it takes the Earth, at the present time, to rotate once is
86,400.002 seconds compared to 86,400 seconds back in 1820. The rotation has
slowed roughly only by 2 milliseconds since 1820. That seems like an insignificant
amount of time BUT over the course of the planet's entire lifetime, it has had very
profound effects on the geophysics of the planet.

It has caused mountains to rise, earthquakes, etc. to occur as we will see. This article
is about, factoring in the tremendous geophysical activity that was caused, by the
Earth's slowing rotation; in the interior of the planet, its crust, oceans and atmosphere
over its entire lifetime.

A replica of Zhang Heng's
seismometer, the houfeng didong
yi, featured in the Chabot Space &
Science Center in Oakland,
amount of information, it took until 2007 to complete the reconstruction.

In 1951, Chinese scientists from China’s National Museum worked on recreating Zhang
Heng’s seismograph. Since there was a limited amount of information, it took until
2007 to complete the reconstruction.

In comparison, it wasn’t until the 18th century (AD), about seventeen hundred years
later, that there was any record that Western scientists even worked on developing a
Zhang Heng
Zhang Heng (simplified Chinese: 张衡; traditional
Chinese: 張衡; pinyin: Zhāng Héng; Wade–Giles: Chang
Hêng; AD 78–139) was a Chinese astronomer,
mathematician, inventor, geographer, cartographer,
artist, poet, statesman, and literary scholar from
Nanyang, Henan. He lived during the Eastern Han
Dynasty (AD 25–220) of China. He was educated in the
capital cities of Luoyang and Chang'an, and began his
career as a minor civil servant in Nanyang. Eventually, he
became Chief Astronomer, Prefect of the Majors for
Official Carriages, and then Palace Attendant at the
imperial court. His uncompromising stances on certain
historical and calendrical issues led to Zhang being
considered a controversial figure, which prevented him
from becoming an official court historian. His political
rivalry with the palace eunuchs during the reign of Emperor Shun (r. 125–144) led to
his decision to retire from the central court to serve as an administrator of Hejian, in
Hebei. He returned home to Nanyang for a short time, before being recalled to serve in
the capital once more in 138. He died there a year later, in 139.

Zhang applied his extensive knowledge of mechanics and gears in several of his
inventions. He invented the world's first water-powered armillary sphere, to represent
astronomical observation; improved the inflow water clock by adding another tank; and
invented the world's first seismometer, which discerned the cardinal direction of an
earthquake 500 km (310 mi) away. Furthermore, he improved previous Chinese
calculations of the formula for pi. In addition to documenting about 2,500 stars in his
extensive star catalogue, Zhang also posited theories about the Moon and its relationship
to the Sun; specifically, he discussed the Moon's sphericity, its illumination by
reflecting sunlight on one side and remaining dark on the other, and the nature of solar
and lunar eclipses. His fu (rhapsody) and shi poetry were renowned and commented on
by later Chinese writers. Zhang received many posthumous honors for his scholarship
and ingenuity, and is considered a polymath by some scholars. Some modern scholars
have also compared his work in astronomy to that of Ptolemy (AD 86–161).
This model of Zhang Heng's seismograph stands in the Ancient Observatory in
Beijing. It is about 5.5 feet tall. The modern signs indicate the compass
Detailed view of the dragon's head with the frog receptacle.
The seismometer (候風地動儀 hòufēng dìdòng yí) that Zhang Heng invented in 132 AD
was an urn with some type of pendulum apparatus contained within it. We don't know
the exact mechanics because they were lost in history. The pendulum was extremely
sensitive to vibration. When it swung it released a ball from the mouth of one of eight
dragons and the ball fell into the mouth of a patiently waiting frog. The loud clang that
resulted notified attendants of some sort of seismological event. It is said that one day
the ball fell but people in the court felt nothing. A few days later a runner arrived from a
village 400 miles away to inform the Emperor that his area had been devastated by an
earthquake. While Zhang Heng's seismograph couldn't predict a quake it could notify
the court when one occurred so that aid could be sent.

China has been plagued by quakes through history. The most recent major quake was
the Tangshan earthquake in 1976 measuring 8.2 on the Richter scale. Tangshan is on
the north China plane. The quake killed more than a quarter million people. There is
frequent activity along the Gansu Corridor, the Shanxi plateau, the Xi'an (Chang'an)
area, the Beijing area, and the western and northern edges of the north China plain. In
the east, from Shenyang in the north to Nanjing in the south, there are moderately
frequent quakes. The western provinces of Sichuan, Yunnan, Tibet, and Xinjiang also
have high levels of quake activity. In the south quakes are centered on the Fujian coast
and Taiwan. For that reason, China is a major source of earthquake detection and
prediction research. Historical records are of great interest to study both the risk level
and to look for patterns over time. As part of that research, Feng Rui and Yu Yan-xiang
(2006, Institute of Geophysics, China Earthquake Administration) concluded that the
earthquake that first set off Zhang Heng's seismograph was magnitude 7 in Longxi with
an epicenter at Tianshui on December 13, 134 AD.