Draft: this lesson was written with AI help and has not yet been read by a human editor.
1 What your class asks
This lesson asks you to describe what affects the flow of fluids, and to compare how fluids are used and their flow regulated in living things and in machines. The museum offers one machine, a water clock whose tank keeps its level, and one living system, the route of the blood through the heart and lungs. Factors such as the thickness of the fluid or the width of the pipe, and any measurement of flow, are for the class to investigate. 1
Curriculum expectations, with their official codes
- C2.8 describe factors that affect the flow of fluids
- C2.10 compare how fluids are used and how their flow is regulated in living organisms and in mechanical devices or systems
2 The lesson
What keeps the flow steady, and what sends it one way?
The expectations ask for factors and for a comparison. For each of the two records, write what moves, what pushes or guides it, and what prevents it from going the wrong way.
Go deeper
Behind the display of the castle clock, a reservoir float descends with the water and transmits movement through ropes and pulleys 2. A separate chamber has another float and a conical plug: when the water rises it closes the inlet, and when it falls it lets more in, so that the level stays approximately steady 3. One float provides motion through descent and the other regulates the feeding chamber, and a further regulator changes the position of the outlet for the required duration 4.
Why they did it
Ibn al-Nafis did not set out to write a book of his own: his aim was to explain Ibn Sina's anatomy, and when he reached the heart he departed from Ibn Sina and from Galen before him 5. For al-Jazari the records preserve no stated reason for the clock. They show how he worked: the author reports failed geometric divisions, then measures the water discharged in a fixed hour and sets the scale positions by calculation and experiment before engraving them 6.
Two views
West's article does not dispute that Ibn al-Nafis described the passage of blood through the lungs about three hundred years before anyone in Europe; the question it raises is whether Servetus and those after him knew his work 7. Servetus's words on the septum and the lungs resemble Ibn al-Nafis's, but a 1940 study by Owsei Temkin pointed out inconsistencies, and the 1547 Latin translation of another of his books apparently said nothing about it 7. West writes that many historians believe Servetus did not know the work; if so, both deserve credit, each in his own time 7.
Think about it
In the castle clock, a float and a plug keep the tank at one level. In Ibn al-Nafis's account, a wall thicker than the rest of the heart stops the blood from crossing and sends it through the lung. Which of the two is a part that regulates how much flows, which one decides where it flows, and what in the records is your evidence?
Into the museum
- The castle clock: floats, a plug and an operator who resets the machine.
- The pulmonary circulation: the two routes of the blood, Galen's and Ibn al-Nafis's, side by side.
- Ibn al-Nafis: the physician, and what the records say of his life and works.
- Al-Jazari: the engineer, his patron and his book.
Try this
Read about the castle clock and the pulmonary circulation. Draw each as a line with arrows from where the fluid starts to where it ends, and mark every place where something steers it.
3 Carry it further
Where this lesson leads in the museum.
4 Check yourself
Nothing here is marked or sent anywhere. It is for you.
In your own words: what does Al-Jazari's castle water clock have to do with this lesson?
Compare with the card
A tank that keeps its level. In the record on al-Jazari's castle clock, a float in a reservoir descends as the water falls and passes its movement on through ropes and pulleys. A falling level in an unregulated tank changes the conditions under which the water leaves, so another chamber has its own float and a conical plug: rising water closes the inlet, falling water lets more in, and the level stays approximately steady. What decides how fast water leaves a tank?
In your own words: what does Pulmonary circulation have to do with this lesson?
Compare with the card
The blood's route through the lungs. The record defines the pulmonary circulation as the blood's route from the right side of the heart to the lungs, and from the lungs to the left side. It says that Ibn al-Nafis wrote, against Galen, that blood does not cross the wall between the ventricles through pores, because that wall is solid, and that it reaches the left ventricle from the lung. Where, in a body or in a machine, must a fluid be made to take one route and not another?
I can now
Notes
- 1. Ontario Ministry of Education, The Ontario Curriculum: Science and Technology, Grades 1–8 (2022)
- 2. Al-Jazari — Donald Hill translation1974, pp.20–22,editor-notes-I.1
- 3. Al-Jazari — Donald Hill translation1974, pp.21–22,24
- 4. Al-Jazari — Donald Hill translation1974, pp.20–22,24–25
- 5. John B. West, 'Ibn al-Nafis, the pulmonary circulation, and the Islamic Golden Age' (2008), pp. 1877–1880, §Ibn al-Nafis
- 6. Al-Jazari — Donald Hill translation1974, pp.17–18,24–25
- 7. John B. West, 'Ibn al-Nafis, the pulmonary circulation, and the Islamic Golden Age' (2008), pp. 1877–1880, §Pulmonary circulation