The Peacock Clock is the sixth machine described by al-Jazari in his famous treatise of mechanics Al-Jami‘ bayn al-‘ilm wa 'l-‘amal al-nafi‘ fi sina‘at al-hiyal (A Compendium on the Theory and Useful Practice of the Mechanical Arts). It is a fascinating water clock and is the only one in the treatise that does not feature any figures of men, instead time is told with the aid of one peacock, two peachicks, and one peahen. This article describes its complex mechanism with 3D animations.
Most of the clocks constructed by early Muslims seem to be characterised by a combination of both engineering and artwork. They would tell time, but would also look pleasing, make musical sounds and generate entertaining movements of a mechanical puppet theatre of human figurines, beasts and birds. Such features generated ingenious ideas and mechanisms in the form of camshafts, escapements, complex gears, control systems and reciprocating pumps.
The Peacock water clock is one of the unique clocks mentioned in Al-Jazari’s book of Al-Jami ‘ bayn al-‘ilm wa ‘l-‘amal al-nafi ‘ fi sina ‘at al-hiyal (A Compendium on the Theory and Useful Practice of the Mechanical Arts). Details of its construction and operation are described quite explicitly in chapter six. This is the one clock that does not feature any human figurines, instead time is told with the aid of one peacock, two peachicks, and one peahen. It uses a tipping bucket to divide time. At the end of this paper are fully labelled diagrams of the clock and should be used as a reference for all components.
We follow in our study of al-Jazari’s device his own narrative, but our description given below is not concerned with exact details of its construction but concerned with how components are linked with each other and with the purpose of the clock and its functioning. The analysis thus provided is conceived to accompany computer animations; it is also an interpretation of the clock’s appearance to viewers and a study of its internal workings. Further, basic notes on the clock’s operating system have been provided to aid understanding of components.
Al-Jazari was an outstanding mechanical engineer. His full name was Badi’ al-Zaman Abu-‘l-‘Izz Ibn Isma’il Ibn al-Razzaz al-Jazari. He lived in Diyar-Bakir (in Turkey) during the 6th century H (late 12th century-early 13th century CE). He was called Al-Jazari after the place of his birth, Al-Jazira, the area lying between the Tigris and the Euphrates in Mesopotamia. He served the Artuqid kings of Diyar-Bakir for several decades (at least between 570 and 597 H/1174-1200 CE) as a mechanical engineer. In 1206, he completed an outstanding book on engineering entitled Al-Jami’ bayn al-‘ilm wa-‘l-‘amal al-nafi’ fi sinat’at al-hiyal in Arabic. It is interesting to note that a placard next to his grave, signed by the District Office, gives his birth year as 1153 in Cizre (Jizre) and mentions he left to Diyar Bakir where he stayed 25 years after which he returned to Cizre where he died in the year 1233. This is a contrast to the information we have the oldest extant copy of his book (preserved in Topkapi Sarayi Libray, Ahmet III collection, MS 3472) which was completed by Muhammad ibn Yusuf ibn ‘Uthman al-Haskafi at the end of Sha’ban 602 H/ 10 April 1206. From Al-Haskafi’s colophon we learn that Al-Jazari was not living at this date. This leads to conclude that he must have died in the year 602 H/1206, just a few months after he had completed his work. But this contradicts what the District office claims.
Al-Jazari’s book was a compendium of theoretical and practical mechanics. George Sarton writes:
“This treatise is the most elaborate of its kind and may be considered the climax of this line of Muslim achievement”
Al-Jazari’s book contains 50 mechanical devices, along with minute instructions on how to construct them, providing an invaluable contribution to the history of engineering. The devices are grouped into six categories:
1) ten water and candle clocks.
2) ten vessels and figures suited for drinking sessions;
3) ten pitchers and basins for phlebotomy and washing before prayers;
4) ten fountains that change their shape alternately and machines for the perpetual flute;
5) five water-raising machines;
6) five miscellaneous devices.
British charter engineer and historian of Islamic technology Donald R. Hill (1974) who held a special interest in Al-Jazari’s achievements wrote:
“It is impossible to over emphasize the importance of Al-Jazari’s work in the history of engineering, it provides a wealth of instructions for design, manufacture and assembly of machines”
In their paper, Ludlow and Bahrani raised the important point that it is more than likely that there is more on the subject in some of the thousands of Arabic manuscripts in the world libraries which have not yet been inspected closely, and obviously require looking into.
For other details on Al-Jazari’s work see the book 1001 Inventions: The Enduring Legacy of Muslim Civilisation, chief editor Salim al-Hassani, National Geographic, 2012 and in articles that can be consulted online on www.MuslimHeritage.com (see especially the two folders devoted to Islamic technology: Al-Jazari and Taqi al-Din).
A drawing of how the clock looks like is given at the beginning of the relevant section of the treatise, see Fig.1 on the right.
See 3D animation of the front showing the sequence of movements of the Peacock above (Animation 1), Peachicks and the Peehan.
At the top of the clock are 15 glass roundels, and during the day, the roundels are red to indicate the hours past. During the night, these roundels are illuminated with candlelight as the hours go by.
Below the roundels is a peahen with her tail out and neck outstretched as if to make a display. Below here are two peachicks facing each other, ready to have a fight. Below the two is a peacock standing alone.
During each half-hour, the peahen will slowly rotate round to face the right. At the end of each half-hour interval a number of events will occur:
The above will occur at every half hour for all the hours of the day, and will continue throughout the night, but with the addition of a lit candle behind the crescent disc. Thus, as the hours of the night go by, the crescent disc will rotate to reveal light through the roundels.
For an overall view of the components of the clock, see 3D animations. Below >
They show the inner workings of the various parts and their interactions.
Animation 10, which shows of the inner workings of the various parts and their interactions.
The clock uses a reservoir to store its potential energy, and its description will begin from there. All parts of the clock will be described in order of parts affected by the water leaving the main reservoir.
The main source of water comes from the main reservoir and its working principle is similar to that of an inflow clepsydra, see Fig. 2. There is a continuous supply of water to the reservoir, and this comes from either a river source, or from a large cistern with enough water for the day. About 20kg of water is contained in the reservoir, and the excess water would escape out of an overflow channel in the sidewall of the reservoir. At the bottom of this reservoir is a short channel, with an onyx at its free end for water to flow out on to the tipping bucket. The onyx is calibrated to size, as to allow the tipping bucket to fill up with water in half-an-hours time.
The purpose of the overflow in the main reservoir is to keep the head of water constant, and thus the outflow rate will not vary, thus ensuring accurate timekeeping.
The tipping bucket is the device that triggers all the mechanisms around the clock at 30-minute intervals. There is a small float in the tipping bucket, and this will rise as the bucket fills with water. At the tip of the bucket is an arm that is part of a clever linkage.
The float is connected to a pulley system that turns the peahen, so that as the float rises, the peahen will rotate, see Fig. 3. There is a weight at the other end of the rope, which is lighter than the float, and this keeps the rope taut at all times. The peahen is initially facing to the right, and the pulley system will turn the peahen 180o to its left in half-an-hour.
The tipping bucket can contain about 20 kg of water before tipping, and this is achieved by careful positioning of its pivot point and correct counterbalancing.
When the bucket tips, it will empty its contents into a trough, but when the bucket returns to its original position, it will turn a gear wheel by an increment of one tooth. The arrangement of the linkage allows the bucket to tip without engaging the gear, but can only engage on the return stroke. This is analogous to a ratchet, as the tipping bucket can only rotate the gear in one direction, and it can only rotate in favour of the tipping bucket. The gear wheel is prevented from rotating the other way, by another ratchet placed near its top.
The main gear wheel is part of a pulley system that turns the crescent disc behind the roundels at the top.
There are 15 glass roundels to correspond with the maximum number of daylight/night hours. For example, on the summer solstice there are 14.5 hours of sunlight, and 9.5 hours of the night, and vice versa during the winter solstice.
There is a disc behind the roundels, and half of its edge is painted red, and the other half is cut away. This is similar to the crescent disc as described for the castle water clock, see Fig. 4. The difference in edges is for day and night use. During the day, the crescent-disc will rotate to show red through the roundels, and through the night the roundels will reveal light, (a candle is lit and placed inside the clock at night).
Mentioned before was the gear wheel connected to the crescent-disc via a pulley system, thus the crescent-disc also rotates at 30-minute intervals, and increments of 1 tooth spacing of the main gear wheel. The spacing on the gear wheel is such that on the first half hour, only half a roundel is revealed, and after the second half of the hour the rest of the roundel is revealed.
The water from the tipping bucket collects in the trough, and through a spout at the bottom, the water flows over the scoop wheel. This will turn the scoop wheel, and provide motion to the three peacocks.
For the two peachicks ‘fighting’, there is a long rod extending from the base of each peacock, see the video and Fig.5 below. The peachick is able to move about its base when the rods are moved left and right.
The rod arrangement is different for each peachick, and thus the motion of the peachick would be more varying, and the quarrel more intense.
The rod extends to the scoop wheel, and lies in between two scoops. So as the scoop wheel rotates, the rods are disturbed and motion is given to the peachicks.
The scoop wheel is also connected to the lower peacock through a system of gears. The scoop wheel rotates about a horizontal axis, but rotation is translated to a vertical axis, through the arrangement of gears, to turn the peacock.
Water falls from the scoops and collects in another trough with a spout at the bottom, and into an air vessel.
The vessel is sealed except for three pipes connected to it, the inlet from the scoop wheel trough, the air channel for the flute, and the vessels siphon, see Fig. 6 (below).
Water will enter the vessel and while it is being filled with water, the air is being forced out of the air channel and through a flute. This flute is then audible and onlookers will believe that it is the sound from the two fighting peachicks.
The vessel must fill up to the bend of the siphon, thus it should hold about 20kg of water, and water released from the siphon would flow back into the river source or collected in a cistern.
That completes the description of the Peacock Clock.
To conclude the description of how this clock works, a schematic of the clock is given. For a clear view and understanding of how the various internal components are connected, three diagrams of the front, side and rear views are shown.
Al-Jazari does not explain why he chose a Peacock in this clock and in his handwashing device (wudhu’ machine). He has, however, used falcons in his other clocks, also without explaining the reason. We are however aware that a Peacock clock is mentioned in the famous folk tales during the Islamic Golden age, known as 1001Nights. Spread throughout these tales, are mentions of numerous real and fictional devices and processes. Amongst these is a clock that sets time and rings every hour. It has the form of a peacock using the movement of his wings to measure/set time (Ebony Horse tale 1/534). This would have not been a fictional water clock as at the time water clocks were well known in Baghdad. We know, for example, that Caliph Harun al-Rashid gifted a water clock to Charlemagne (the Holy Roman Emperor) that fascinated him and his court in Aachen. Also, Hasan ibn al-Haytham, who lived at the time, constructed a novel water clock, which he described in one of his manuscripts, see this article.
One cannot tell whether Al-Jazari was aware of the 1001Nights tales. If he was, he would have mentioned it as he did not hesitate to explicitly and/or indirectly refers to the works of Hero, Philo, Archimedes, Banu Musa, al-Muradi and Ridwan al-Sa’ati– drawing upon the technical achievements and mechanical peculiarities of their works even while noting very quickly how he has tried to further refine and more importantly, depart from their mechanisms. We still remain unaware of the reason why these earlier clocks and devices used falcons.
Of course, Peacocks have been a symbol of wealth, beauty and rebirth since ancient times and were a favourite motif in ancient civilisations as well in recent times.
One of the most fascinating Peacock clocks is a large automaton featuring three life-sized mechanical birds. Unlike that of Al-Jazari’s water Peacock clock, it is a mechanical clock that uses escapements connected to a winding mechanism.
The clocks original form was manufactured by the London jeweller and goldsmith James Cox in the 2nd half of the 18th century. Today the clock is a prominent exhibit in the collections of the Hermitage Museum in Saint Petersburg. The clock is also shown daily on the Russian TV channel Russia-K. The Russian mechanic Ivan Kulibin is said to have set it in working order. From 1797 to the present day the Peacock Clock has been one of the Hermitage’s most famous exhibits. It is, moreover, the only large 18th-century automaton in the world to have come down to us unaltered and in a functioning condition.
This research was carried out twenty years ago. It would have not been possible without the hard work of my students, especially Miss Wai Yin Chang and Mr. Jonathan W. B. Chang, who assisted in the research work for the Foundation for Science, Technology and Civilisation, as part of their research project at the University of Manchester. I like to express thanks to Dr Terrence M P Dugan of Akdeniz University for reminding me of the Peacock clock mentioned in the 1001Nights tales and also to Mr Avi Golan who pointed out his recent work on the physical construction of the mechanism of Al-Jazari’s peacock clock shown in this video.
Al-Jazari, The Book of Knowledge of Ingenious Mechanical Devices: Kitáb fí ma’rifat al-hiyal al-handasiyya, translated by D. R.. Hill. Dordrecht: D. Reidel, 1974.
Al-Jazari, al-, Al-Jami’ bayn al-‘ilm wa ‘l-‘amal al-nafi’ fi sina’at al-hiyal. Edited by Ahmad Y. al-Hassan. Aleppo: Institute for the History of Arabic Science, 1979.
Al-Muradi, Introduction to the English version of ‘The Book of Secrets in the Results of Ideas’, edited by Leonardo Research Centre for the Qatar Museums Authority.
Salim T S Al-Hassani (ed.) “1001 Inventions: The Enduring Legacy of Muslim Civilisation” National Geographic, 2012. Also: “1001 Inventions: The Enduring Legacy of Muslim Civilization: Reference (4th) Edition Annotated, Text only”, https://www.amazon.co.uk/gp/product/B0775TFKVY.
Salim Al-Hassani, The Machines of Al-Jazari and Taqi Al-Din (2004).
Hariri, “Study and Analysis of the Water Machines in the book entitled ‘A Compendium of the Theory and Practice of the Mechanical Arts by al-Jazari’. Applying Modern systems on Control Engineering”. Master Thesis. Aleppo: Aleppo University (in Arabic), 1997.
D R Hill, “Mechanical Engineering in the Medieval Near East”, Scientific American, May 1991.
D R Hill, Arabic Water Clocks, University of Aleppo, Institute for the History of Arabic Science, 1981.
Ananda K. Kumarasvami, The Treatise of Al-Jazari on Automata: Leaves from a Manuscript of the Kitab fi Ma’arifat al-Hiyal al-Handasiya in the Museum of Fine Arts, Boston, and Elsewhere. Boston: Museum of Fine Arts, 1924 (Communications to the trustees, VI).
C G Ludlow and A S Bahrani, “Mechanical Engineering during the Early Islamic Period” , I. Mech. E, The Chartered Mechanical Engineer, 1978, pp. 79-83.
George Sarton, “Introduction to the History of Science”, 1927, vol. 2, p. 510. Also: Krieger Publishing (31 Dec. 1975).
 Al-Hassani, Salim, The Machines of Al-Jazari and Taqi Al-Din (2004). Also, see:
 Al-Jazari, “The Book of Knowledge of Ingenious Mechanical Devices: Kitáb fí ma’rifat al-hiyal al-handasiyya”, translated by D. R. Hill. Dordrecht: D. Reidel, 1974.
 George Sarton, “Introduction to the History of Science”, 1927, vol. 2, p. 510. Also: Krieger Publishing (31 Dec. 1975).
 Donald Hill, “Mechanical Engineering in the Medieval Near East”, Scientific American, May 1991, pp. 64-9.
 C. G. Ludlow and A. S. Bahrani on “Mechanical Engineering during the Early Islamic Period” , I. Mech. E, The Chartered Mechanical Engineer, 1978, pp. 79-83.
 Salim T S Al-Hassani (ed.) “1001 Inventions: The Enduring Legacy of Muslim Civilisation” National Geographic, 2012. Also “1001 Inventions: The Enduring Legacy of Muslim Civilization: Reference (4th) Edition Annotated, Text only”, https://www.amazon.co.uk/gp/product/B0775TFKVY.
 Yuna Zek, Antonina Balina, Mikhail Guryev, Yuri Semionov: The Peacock Clock – photos, history and description of the Peacock Clock at hermitagemuseum.org (website of the Hermitage Museum, archived version)