Month: February 2019

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Automatic Wuḍūʾ (الوضوء‎) Pitcher and Errors by Engineers

Introduction

Al-Jazari opens this chapter with the wish of King Salih Nasreddin Mahmud, the third Artuqid king that al-Jazari was serving:

“King Salih disliked a servant or slave-girl pouring water on to his hands for him to perform his ritual ablutions and he wished me to make [something]for pouring water onto his hands for his ritual ablutions.”

The specific reference to ” a servant or slave-girl ” is a bit odd but al-Jazari responded to the challenge and made an “automatic” pitcher.

“Automatic” Pitcher, Topkapi manuscript, 1206.

A servant brings the pitcher and put it on a pedestal; it is a relatively large handsome pitcher. The duck whistles then the water begins to flow from the spout. There are quite a few whistling systems in al-Jazari designs, but this pitcher has no mechanism for the whistling which was probably forgotten. It made me look into error in the book and think about proofreading and editing.

How does it work?

The technical explanation, very minimal this time, will be colored in blue, so anyone who is not interested in siphons can skip those bits. Below is a drawing by the book translator and annotator Donald R. Hill that I edited and attached captions, all remaining errors are my own.

A drawing by the book translator and annotator Donald R. Hill

 

The pitcher is divided into two horizontally, the bottom part until the partition (orange al-Jazari original drawing) and top from the partition till the pitcher’s neck. The Pitcher spout, designed in the shape of a duck’s neck, is a Siphon almost touching the partition. A Siphon is a tube in an inverted ‘U’ shape, which causes a liquid to flow upward with no pump but powered by the pull of gravity. I wrote quite a bit on siphons, for example here. The atmospheric pressure pushes the liquid up in the tube only if the pipe is full of water. In the beginning, the servant pours water until the float submerges. The water level is too low, below the curve in the duck’s neck and no water will come out of the spout. The cover is also divided into two, and the top is separated from the bottom with a valve and a rotating plug. The servant pours water to the top part of the cover, put the pitcher on the pedestal and rotates the knob. The plug has a pipe through and when rotated will allow water down to the tipping bucket. The latter, when full will tip and release its water so the water level will rise into the neck and the ritual ablution begins. Al-Jazari wrote that the pitcher would whistle to notify the King that the purification is starting, but there is no indication, in the drawing or the text of a whistle. You should be aware that al-Jazari made frequent use of whistles based on compressed air and an intelligent engineer should not have difficulty to implement one here.

 

Errors and Proofreading

The missing whistle is not the only error in the book. For example, in the Elephant Water Clock al-Jazari writes that the two chains from the float upward connect to a single ring. This is clearly wrong because each chain is connected to another Dragon. There are probably more mistakes. Also, I’m just beginning to study Arabic and cannot detect errors in spelling or grammar.

The issue of errors in the text is on my mind because when I translate my post to English, I always find some errors in the original text. It can be minor typos, it can be real errors. Sometimes I think that mistakes (typing, proofreading, and essence) are like socks, whatever you’re doing, there’s always missing socks in the laundry, and unlike many pieces of advice online the socks are neither behind the washing machine nor inside the bed covers but simply disappeared forever. Despite the proofing, efforts and the goodwill there are always some individual errors that find their way into the text. My love M. read this text and told that the analogy is not working because socks disappear and errors remain. I think that in my head the two are connected because they are an impudent violation of the law of conservation of mass which states that for any closed system, the mass of the system must remain constant over time. Well, socks disappear, and errors appear from thin air.

I know some people are gifted editors or proofreaders, I think it takes a different set of characteristics than the qualities of good engineers. Obviously, a good editor who has deep knowledge of the language and understands the content can see what is clear and what is not and ask questions that help reveal errors. Engineers’ education does not emphasize the choice of words (what you say) nor style (how you say it) and writing quality, in general, is overlooked. Most engineers are more proficient in mathematical clarity rather than writing with clarity. The editor and the proofreader are naturally very skilled readers, and sometimes writers in their own right. There are certainly engineers who read literature although in my experience not that many. Additional attributes, required for an editor or the proofreader, are less obvious to me, and I don’t know how I can learn them. You need a great eye for errors. I read very fast, because of the ability to distinguish between what is important and what is less so. I’m not exactly flipping pages but I “correct” the text as I read and therefore ignore errors. I think patience in reading is required to see the existing version as well as alternative formulations. This is quite the opposite of the education of an engineer which is more directed to purposeful reading and extracting the meaning. Any good text needs a committed editor and meticulous proofreader. I certainly am not both, and I doubt they were available in Diyarbakir. If this is true no one need to wonder about errors the remained in al-Jazari’s book but to remove his hat in awe because they are so few of them.

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Pump powered by a water wheel

This post is dedicated to Gedalya and Aba Neeman (grandfather and great-grandfather of my love). On their tombstones engraved “Loved the work and manufacturing of water pumps in the land of Israel.”

 introduction

This revolutionary water pump is the fifth  pump in Category V which is dedicated to “machines for raising water from pools, and from wells which are not deep, and from running streams.”

Fifth water pump, Topkapi manuscript,1206

Al-Jazari won his fame mainly because of exotic water clocks full of surprises like the Castle water clock or The water clock of the peacocks(in Hebrew) and wonderful automata like The Arbiter for a drinking session and many more. This pump, like the four pumps in previous chapters, shows that al-Jazari was involved in the real hardship of the people around him. Water pumping is essential to any society, for drinking water, watering crops, for excess water and flood pumping, during fire extinguishing and more.

The common pumps in the world of Islam in the 12th century were the Shaduf (Arabic شادوف) and the Saqiya (Arabic ساقية). Both are ancient irrigation tools for raising water. The Shaduf is fully manual and consists of an upright frame on which suspends a long pole with a bucket at one end a counterweight at the other. The operator pulls the rope until the bucket is full of water. With the help of the balancing weight, he lifts the bucket and pours them into the irrigation canal. The Saqiya is a mechanical device raising a chain of buckets or pots using a donkey or an ox to raise the water.

These two pumps are quite similar to a human using a bucket to raise water, only saving work and effort.  The water wheel pump does not imitate the human action and can be seen as an extension and development of the piston pump of Ctesibius (Κτησίβιος), a Greek inventor and mathematician in the golden period of Alexandria, in Ptolemaic Egypt. He wrote the first treatises on experiments with compressed air which earned him the title of “father of pneumatics”. He invented the first piston pump which was apparently very popular in the Roman Empire. At least twenty five such pumps were found in excavations of Roman sites. You can read more here. None of Ctesibius writing survived, we know of him only because of later writers quoting his work. I don’t know about Ctesibius pumps in the Muslim world, and there is no reference to Ctesibius in al-Jazari’s book. We shall never know what, if any, information about Ctesibius was available to al-Jazari.

How does al-Jazari water wheel pump work?

The technical explanation, as always, will be colored in blue, so anyone who is not interested in intake or discharge valves can skip those bits. This is a short YouTube clip from “Technology Science in Islam” explaining the operation of the pump:

The energy source of the pump is the water wheel, turning by water flow. The water wheel is connected through gears to a wheel with an eccentric pin (positioned not in the Center) within a rail inside the crank connected to a fixed point. When the wheel turns the rod moves left, and one piston is pulled, and one piston is pushed. This mechanism is called a slider crank mechanism, and it converts straight-line motion to rotary motion, as in a reciprocating piston engine, or to convert rotary motion to straight-line motion, as in a reciprocating piston pump. This mechanism is essential to modern machinery.

Slider crank mechanism

Two pistons are attached to suction pipes going down to the river. The suction pipes continue upward and come together to a single supply. The suction pipe has two directional one-way valves called the intake valve and discharge valve. This is a modified drawing of the piston and the valves. In al-Jazari original drawing there is no water, and both valves are closed, which is possible only during construction and impossible during pumping. In addition, in the facsimile edition, the drawing is cut:

Piston and valves, modified drawing

When the piston moves backward (as in the drawing), the intake valve opens, and the discharge valve is closed. So the pump is disconnected from the supply line and draws water from the river. When the piston moves forward (pushed) the intake valve closes, and the discharge valve opens, and water is pushed upward in the supply pipe. This mechanism is called double action because when one piston is being pushed the second piston is being pulled, so the water supply is continuous.

There are three major innovations in al-Jazari’s pump in comparison to Ctesibius pump. Each one would justify a separate patent today. In the Web, there are lists of what al-Jazari invented, for example, here or here. The discussion on the right for a patent is foreign to al-Jazari and the 12th century in general. In a future post, I hope to write about the history of patents and the concept of intellectual property in The Book of Knowledge of Ingenious Mechanical Devices.

  1. The piston pump of Ctesibius was a manual pump and requires a person to operate it. Al-Jazari used a water wheel to power the pump. Al-Jazari also writes that the water wheel is like the one used to rotate millstones which were well known at his time. This is a big advantage in pumps for drinking water or irrigation
  2. The use of waterwheel demanded to convert circular motion (water wheel) to linear motion (motion of the cylinders). History of the crank (in various forms) is documented from the 2nd century BC in China. Al-Jazari knew the book by the “Banu Musa” which includes a crankshaft. But the crank-slider mechanism is more efficient and remains in use to this day, without significant changes.
  3. Ctesibius’s pump only works when immersed in water. If the water level decreases, it will cease pumping. The al-Jazari’s pump has suction pipes that allow it to function properly above the river water level. A decrease in water level (up to a point) should not affect it at all.

Was this pump built or is it just an idea?

Occasionally someone wonders if al-Jazari indeed built his machines or were they just fantasy blueprints or suggestions that never materialized? Unfortunately we don’t have any proofs. The Palace in Diyarbakir was only partially excavated and there is no archeological evidence of al-Jazari machine. I don’t know any external evidence, for example, a Muslim traveler visiting the Palace in the 13th century who was able to report one of the exotic machines like the elephant clock. However, I’m convinced that the pump, like the Palace door and Castle clock, described in previous posts, were indeed built. I have two arguments:

  1. The number and level of details make you feel that this pump was built. For example,  a rope wrapped on the copper piston to improve sealing. The very use of the rope is a hint of an improvement cycle. It is hard to assume that this was a part of a design which never came to life. Moreover,  al-Jazari is very specific and requested a rope made from cannabis used at his time by sailors. This rope was selected, probably, due to its resistance to water. Could it be that al-Jazari thought about all these details although the pump was not built? Possible but not very likely.
  2. In 1976 the London Science Museum built an accurate model of the water wheel pump. The only difference was that the pump was powered by electricity and not by the Thames. A picture of the model is below. The model produced a steady stream of water with zero problems. It is possible that al-Jazari was a wonderful designer and the museum team was the first to realize his design that just worked great on the first try. It is more likely to think, and experience quite often proved it, that the shift from the drawing board to a real machine requires iterations and improvements. The Museum staff’s success relies thus on the practical experience of al-Jazari’s pump.

    Pump reconstruction. London Science Museum

    Aba Neeman Pumps Ltd.

    In 1980 I learned Chemistry at Tel Aviv University and I was looking for a summer job for my livelihood. I don’t remember exactly how it was arranged, but I went to work in the factory “Aba Neeman Pumps Ltd”, that was owned and managed by the grandfather of my love, Gedalia’s Neeman. In my first day in the factory, I helped cast impellers in the sand. Quite similar to what al-Jazari did 800 years before me. I don’t want you to have the wrong impression about my technical skills at the time. I got 5 minutes explanation about the task and until the end of the workday I broke with hammer unneeded bronze parts. The offices were tiny and no one needed my knowhow in chemistry or computers. Most of the summer I was an apprentice of the lathe operator. It was wonderful. I enjoyed it so much that I took an evening course in Lathe operation. The factory was built by Aba Neeman in 1900. He was a real autodidact; His formal studies amounted to a “Yeshiva”, a Jewish educational institution that focuses on the study of traditional religious texts. All he knew about machines was learned from his work and experimentation. He worked in the metalwork workshop of Leon Stein, who did all the metal work required for the young Jewish community in Israel: repairing wagons, maintenance of pumps, and a repair of the steam boiler in the winery in Zichron. In the absence of electricity and engines, the lathe was operated by the movement of the legs like old Singer sewing machines. Such a manual lathe was the beginning of the factory. Aba Neeman specialized in water pumps and amazingly, the only difference between the pump made by Aba Neeman and al-Jazari’s pump, explained above, is that Aba Neeman’s pump was powered by a diesel engine and al-Jazari’s pump was powered by a water wheel. The Author and farmer Moshe Smilanski wrote that “the pump of Aba Neeman was working for  44 years with no problems” ( from “Inventor and Efforts” by Saul Avitsur [Hebrew]). This was not eight hundred years ago, only in the last century but  “the farmer and author” and a pump that holds 44 years sound so far away, something to long for, like al-Jazari.

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The Water Clock of the Boat, a Serpent or a Dragon?

Introduction

The boat clock is a simpler version of the elephant clock. The scribe indicates the minutes passed, and one Dragon (two in the elephant clock) swings on its axis every half an hour. It looks like an early sketch for the elephant clock or a simpler version for beginners. Perhaps, for this reason, nobody wrote, or at least I haven’t found anything, nor restorations or animations, in contrast to the abundance for the elephant clock. The Dragon appears here in more detail and also has a drawing of his own but the text refers to it as a serpent just with legs and wings, it got me thinking about the biblical serpent and the story of the tree of the knowledge of good and evil. This post is dedicated to the serpent-dragon, and on this occasion, I also explain the balancing process that allows the dragon to go for a marvelous swing and return safely on his legs.

The Boat Clock, Topkapi manuscript, 1206.

How does the dragon make a flip and land on his feet?

The technical explanation, as always, will be in blue, so anyone who is not interested in submersible floats, torque, or center of mass can skip those bits. In the water clock of the boat, like the elephant clock, the main mechanism is a sinking float, a float with a hole that sinks slowly for half an hour. After half an hour, the float is full of water and begins to sink quickly, and releases a ball that falls into the dragon’s mouth:

Drawing from the book, Topkapi manuscript, I tilted the dragon to visualize the swing and added the lead weights in his tail and the ball.

The dragon is made of a thin brass plate that was rolled into a pipe and hammered into the shape of a dragon. The dimensions are not very detailed, but the Dragon’s tail forms a circular ring of four fingers, or 8 cm in diameter. The dragon head is hammered separately and soldered to the ring. The Dragon’s legs hold an axle that is free to rotate. The ball I added does not appear in the original drawing, but is described in the text and weighs 30 dirhams (درهم), almost 100 grams. When it falls into the Dragon’s mouth, it generates a torque, causing the dragon to flip. A torque or moment of force is the rotational equivalent of linear force. The torque is given by the cross product of the position vector (distance vector) and the force vector:

Some of the students I taught physics to over the years struggle with cross products, especially with the moment of force. But we all know intuitively that it is easier to open the door by pushing it near the handle than by pushing it near the hinges. (larger r =larger torque). Or when we struggle to remove the lug nuts of a flat wheel, we often use a wrench extension for the same reason – to generate a larger torque.

When the dragon’s head is downwards, the ball falls off, and the lead weight in his tail exerts torque in the opposite direction and resets the dragon’s position. My love, M., said that the dragon is like a roly-poly, and of course, she is correct. This is a round-bottomed toy, usually egg-shaped, that tends to right itself when pushed at an angle, seemingly in contradiction to the force of gravity.

Drawing of a roly-poly

The bottom of the toy is made of a high-density material, such as metal, and thus the center of mass is low relative to the toy’s height. This is very similar to the lead weights in the tail of the dragon. The ball falls into the Dragon’s mouth function as the finger pushing the toy over. In both cases, the low center of mass exerts a torque that reinstates the upright orientation.

Interestingly enough, al-Jazari calls the lead “black lead” (الرصاص اسود) because in his time they called Tin “white lead”. Maybe in a future post, I will write more about the metallurgy of the 12th century.

A Serpent or a Dragon?

Serpentes (snakes) are an elongated, legless, carnivorous suborder of reptiles. They are characterized by the absence of limbs. Al-Jazari’s serpent has wings and legs, making it a legendary creature or a Dragon. Dragons do not exist (sorry if I offended the fans of dragons) and, respectively, do not have a rigid biological definition. A dragon is a large, serpent-like mythological creature that appears in the folklore of many cultures around the world. Beliefs about dragons vary significantly by region, so horns, wings, and the number of legs vary a lot. All dragons have superpowers. We are more aware of dragons capable of breathing fire in the western cultures, but Bakunawa, a dragon from the Philippines, can swallow the moon, and the Vietnamese dragon can control the weather. It can be argued that the Dragon figure was influenced by various snakes, especially spitting cobras; bats (wings); giant lizards; and, in the modern era, extinct dinosaurs. In the Wikipedia entry of the “Elephant clock” appears this wonderful quote in the name of al-Jazari, signifying his “multicultural mentality”:

  “The elephant represents the Indian and African cultures, the two dragons represent Chinese culture, the phoenix represents Persian culture, the water work represents Greek culture, and the turban represents Islamic culture.”

Al-Jazari didn’t write these lines. Such errors are amazing and funny and are one of the risks of a free-content encyclopedia relying on volunteer editors.

In contrast to the threatening figure of the Western Dragon, the Chinese Dragon is a symbol of strength, integrity, and wisdom. The Chinese Dragon is depicted as a lizard-like creature without wings and four clawed feet, and a long tendril appended to each side of the snout. Al-Jazari’s Dragon is not very Chinese. However, at home, we have a facsimile edition of the “Sarajevo Haggadah.” It’s the Passover Haggadah written in Barcelona around 1350 and is considered the oldest surviving Haggadah. The Haggadah is displayed at the National Museum of Bosnia and Herzegovina in Sarajevo, and this is the origin of its name. To my surprise, the Haggadah is packed with dragons. On top of this, in the 19th century in Paris, a small book was printed: – L’ornementation des Moyen-âge. This is a collection of illustrations from medieval manuscripts and also includes many dragons. The dragons in all three books are very similar, with the same general lizard-like structure, an animal head that is not completely defined, small wings, and legs. If my rationality hadn’t so constrained me, I would be convinced that the three illustrators visited some mysterious zoo and made a drawing of the dragon that was held not far from the reptile room.

Right side dragons from Haggadah Sarajevo, in the center the Dragon of the Boat, Topkapi manuscript and to the left a dragon from L’ornementation des manuscrits au Moyen-âge

All this discussion about snakes with legs took me back to the Bible story, Genesis 2-3.  Adam and Eve were in the garden of Eden, where “And out of the ground made the Lord God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.” God allowed Adam and Eve to enjoy the fruits of the Garden except for the tree of knowledge, “for in the day that thou eatest thereof thou shalt surely die. Now the serpent was more subtil than any beast of the field which the Lord God had made.” The Serpent Tempted Eve, claiming, “Then your eyes shall be opened, and ye shall be as gods, knowing good and evil.” Therefore, the snake lost its legs and got in trouble with mankind: “And the Lord God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:

Genesis 2-3 King James Version

But did al-Jazari know the Biblical story about how the ancient serpent lost his feet?

Years ago I visited the Topkapi Museum in Istanbul, and near one of the swords there was a summary of the “The Binding הָעֲקֵידָה Ha-Aqedah” only, Ishmael (and not Isac) is the victim and the hero of the story. First, I thought there was confusion, but this is, of course, just my ignorance. Eid al-Adha ( عيد الأضحى‎) ‘Feast of the Sacrifice’ is the second of two Islamic holidays celebrated worldwide each year. The sacrifice celebrated is the sacrifice Ibrahim (Abraham), our father, was asked by God to sacrifice his son Ismail (Ishmael), though the Qur’an does not name the son. In my eyes, both stories are equally heinous, and already as a child, I remember my inner resistance. Like the story of the Binding, the story of the Garden of Eden in the Quran is completely different:

“And you, Adam, inhabit the Garden, you and your wife, and eat whatever you wish; but do not approach this tree, lest you become sinners.

But Satan whispered to them, to reveal to them their nakedness, which was invisible to them. He said, “Your Lord has only forbidden you this tree, lest you become angels, or become immortals.”

Quran, Surah 7 elevation, Translated by Talal Itani.

In the Quran, there is no tree of knowledge. The only tree mentioned by name is the Tree of Immortality ( شجرة الخلود Shajarat al-Kholoud ). The Serpent is not the seducer but the devil himself, and he is tempting Adam and Eve with eternal life. In Surah 2, The Heifer, Iblis (إبليس) appears, which is another name for the devil in Islam. Eve, as a woman, is the main culprit in the original sin, both in Judaism and Christianity. In Islam, Eve is Adam’s partner and is free from sin.  It is very likely that al-Jazari didn’t know the Serpent from Genesis and knew only the Quranic version and the source of its legs and wings? Who can tell?