Al-Jazari and the Elephant Clock: engineering in the Middle Ages

The year is 1206, and the place is Amid, today’s Diyarbakir. An elderly master craftsman is finishing the last pages of a book he has been working on for years. The pages are full of colourful drawings: an elephant carrying a tower on its back, a boat floating on a lake with figures playing instruments inside it, wheels drawing water from a well. Beside each drawing are the measurements of the parts and the order in which they are to be put together. The master’s name is al-Jazari. Today his book is one of the most closely studied medieval works in the history of engineering.

Twenty-five years at the Artuqid court

His full name was Abu al-‘Izz Isma’il ibn al-Razzaz al-Jazari. He is thought to have been born around 1136. The name “al-Jazari” shows that he came from al-Jazira, the region between the Tigris and the Euphrates; some take it to mean that he was born in Cizre. In his book he tells us that he spent twenty-five years in the service of the Artuqid rulers. At that time the Artuqids were a Turkmen dynasty ruling the lands around Diyarbakir, Mardin and Hasankeyf.

He wrote the book at the request of the ruler Nasir al-Din Mahmud and finished it in 1206. Its long title, al-Jami’ bayn al-‘ilm wa al-‘amal al-nafi’ fi sina’at al-hiyal, means roughly “A useful compendium combining theory and practice in the art of ingenious devices”. The title’s emphasis on ‘ilm and ‘amal, knowledge and practice, sums up the spirit of the book.

Fifty devices in six categories

The book describes 50 devices in six categories:

1. Water clocks and candle clocks
2. Vessels and figures for banquets
3. Devices for hand-washing and ablutions
4. Fountains that change shape, and flutes that play by themselves
5. Water-raising machines
6. Miscellaneous devices (such as doors and locks)

Each device comes with drawings, the measurements of its parts and the order in which it is built. Al-Jazari says that he built most of them himself and wrote the book so that his readers could build them too. That is why the book is not a “catalogue of wonders” but a construction manual.

The Elephant Clock, step by step

The most famous device in the book is the Elephant Clock. From the outside you see an elephant with a tower on its back; the part that actually measures time is hidden in a water tank inside the elephant’s body. A half-hour cycle works like this:

1. A bowl with a small hole in its bottom floats on the water. Water slowly seeps in through the hole.
2. After about half an hour the bowl is full and sinks. The strings tied to the bowl are pulled down.
3. The strings move a seesaw mechanism in the tower, and a ball is released from the top.
4. The ball drops into the mouth of a serpent, and the serpent, now heavier, tips forward.
5. As it tips, the serpent pulls the sunken bowl up out of the water by its strings. At the same moment the elephant’s driver, the mahout, brings down his mallet to sound the half hour (accounts differ on whether the sound came from a cymbal or a drum). The bowl floats again, and the cycle starts over.

So the “brain” of the clock is a small hole. If the hole is larger, the bowl fills faster and the clock runs fast; if it is smaller, the clock runs slow. The real skill in building a water clock lay in getting this hole exactly right. The balls, the serpent and the mahout’s mallet are a show that makes the measured time visible and audible.

The heritage inside the clock

Measuring time with a bowl that slowly sinks in water was not al-Jazari’s invention. The method had long been known in India and Iran, where it was used, for example, to share out turns of irrigation water fairly. The tradition of writing about ingenious devices began in Alexandria, with Philo of Byzantium in the 3rd century BC and Hero of Alexandria in the 1st century AD. In 9th-century Baghdad, the Banu Musa brothers wrote a book describing about a hundred devices.

The elephant, the dragon-headed serpents and the bird figures on the Elephant Clock are sometimes read today as symbols of different cultures. We don’t know whether this reading reflects al-Jazari’s own intentions. What we do know is that the clock’s mechanism is a work in which knowledge from India, Iran, Greece and Baghdad came together in Diyarbakir.

From palace to field: water-raising machines

Al-Jazari’s book is not only about entertainment at court. The fifth category describes five machines that raise water from a well or a river. In some of them an animal turns a horizontal wheel, and the teeth of this wheel turn a vertical one. In another, the motion of a wheel turned by a flowing stream is converted, through a slotted rod, into the back-and-forth motion of two pistons, which take turns sucking water in and pushing it out.

Linkages that turn rotation into back-and-forth motion were known long before al-Jazari. A 3rd-century AD relief on a sarcophagus at ancient Hierapolis, near Pamukkale, shows a stone-cutting saw driven by a water wheel through a crank and connecting rod. So calling al-Jazari “the inventor of the crank” is misleading; his contribution was to bring these principles together in detailed, workable designs.

The “first robot”?

You often come across this sentence online: “Al-Jazari built the first robot.” The real story is more interesting.

One of his automata, a boat that floated on a lake at banquets, carried four musician figures. The drummer’s sticks were raised and lowered by projections on a rotating shaft, in other words by cams. Some researchers suggest that the rhythm could be changed by moving these projections, and that this was a kind of programming; this interpretation is debated.

But programmable devices existed before him. In the 1st century AD, Hero described a cart whose route was set in advance by a string wound around its axle. In the 9th century, the Banu Musa brothers described an automatic flute that played by means of pins on a rotating cylinder. A robot in today’s sense, on the other hand, is a machine that senses its surroundings and acts on what it senses.

The balanced way to put it is this: al-Jazari’s automata are counted among the early examples of programmable automata. What makes him important is not being “first”, but turning this heritage into a detailed, workable and teachable engineering book.

Learning by making

You can hear a workshop in al-Jazari’s book. He describes testing designs with paper models first, gluing wood in layers so that it would not warp, balancing wheels and adjusting water holes one by one. These are habits an engineering student still learns today: try it with a model, measure, adjust, try again.

The tradition lived on after him. In the 16th century the astronomer Taqi al-Din, who would later found the Istanbul observatory, also wrote books on mechanical devices and clocks.

Where can we see it today?

Many manuscript copies of the book survive in libraries around the world, including in Istanbul, and some of its finest illustrated pages are now scattered among museums. The engineer and historian Donald R. Hill published a complete English translation in 1974. In Istanbul, the Museum of the History of Science and Technology in Islam in Gülhane Park displays models of scientific and technological instruments from the Islamic world. And in a shopping centre in Dubai, a large replica of the Elephant Clock is on show.

You can also try a small experiment at home. With an adult’s help, make a small hole in the bottom of a yoghurt pot, float the pot on the water in a washing-up bowl and time how long it takes to sink. Then see what happens when you make the hole bigger. That is the very heart of the Elephant Clock.

Summary

• Al-Jazari (about 1136–1206) spent twenty-five years at the Artuqid court, and in 1206, in Diyarbakir (Amid), he completed his book describing 50 devices.
• In the Elephant Clock, time is measured by a bowl with a hole that sinks in water in half an hour; the falling ball, the tipping serpent and the mahout’s mallet stroke turn this measurement into a show.
• Alongside court automata, the book also includes five water-raising machines for irrigation and water supply.
• Saying that al-Jazari built “the first robot” is an exaggeration; his automata are counted among the early examples of programmable automata and build on the heritage of Hero and the Banu Musa.