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Water that does the work

Describing how two water-driven machines operate (E3.3).

Lesson 1 of 1 3 of 5 in the course

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Draft: this lesson was written with AI help and has not yet been read by a human editor.

What your class asks

This lesson asks you to describe, with the aid of diagrams, how selected energy-transformation technologies operate. The museum offers two water-driven machines from one medieval book, in which flowing water turns a wheel and a shaft; the wind turbines, photoelectric cells and heat engines, and the calculation of energy and efficiency, are for your class. 1

Curriculum expectations, with their official codes

  • E3.3 describe, with the aid of diagrams, the operation of selected energy-transformation technologies […]

Before you start

A thought to carry into the lesson.

The lesson

Where does the energy come from, and where does it go?

Draw the machine as a chain that starts at the water and ends at what it achieves. At each link ask: what moves, what pushes it, and what must be supplied for the chain to keep going?

Go deeper

Follow the energy through the double-piston pump link by link. TDV's description of the drive can be followed step by step 2:

  1. Flowing water turns the wheel.
  2. The wheel drives a gear in a vertical plane.
  3. This engages another gear in a horizontal plane.
  4. A vertical pin near the horizontal gear's rim passes through a slot in a rod.
  5. The rod's other end is fixed by another pin; the piston rods are connected to it.
  6. As the gear rotates, the slotted rod makes an angular movement and the piston rods travel back and forth, operating the pumps.

The record sets beside it the hidden-drive lifter: discharged water passes over a wheel in a chamber beneath the floor, transmitting motion upward 3.

Why they did it

The records give no reason in al-Jazari's own words. They show the practical problem: this is a pump powered by flowing water, not a bucket lifted by hand 2. TDV places the book's fifty devices in six divisions, one of them for water raising 2.

Often misunderstood

"Synchronized" does not mean "at the same moment". Al-Jazari explains alternating action: movement to one side discharges one cylinder while water enters the other through its intake, and the return movement reverses those states 4. Both delivery pipes join one vertical riser, so synchronization means coordinated filling and discharge, not both cylinders necessarily discharging at every instant 5.

How do we know?

The text gives a design height of about twenty cubits, related to the riser's length, but no measured volume per time or documented efficiency test in this passage 4. The museum model of the pump is half-size: its catalogue measurements and weight belong to that model, not to an independently inspected original 6.

Think about it

Hill's text gives a design height of about twenty cubits for the pump but no measured volume of water per time. If you wanted to say how much water the pump lifts each minute, what would you need to measure, and why can the drawing not tell you?

Into the museum

Try this

Read about the hidden-drive water lifter and the double-piston pump. Draw a diagram of each from the supply of water to the water it lifts, and label what must be supplied to keep it working.

Check yourself

Nothing here is marked or sent anywhere. It is for you.

Which of these did you meet in this lesson?

Yes. That is the one from this lesson.

Not in this lesson. Look again at the cards above.

Not in this lesson. Look again at the cards above.

In your own words: what does Al-Jazari's hidden-drive water lifter have to do with this lesson?

Compare with the card

The cow that does not turn the wheel. Al-Jazari describes a pool hiding a wheel and drive below, with jars lifting water to a channel above. A wooden cow seems to turn the machine, but the record says water drives it, and the shaft turns the cow, not the reverse. It adds that the arrangement needs a supply, a drainage path and a fall that lets the water do work; it is not a closed pool creating its own power. Where does the energy come from?

In your own words: what does Al-Jazari's waterwheel-driven double-piston pump have to do with this lesson?

Compare with the card

A pump driven by a stream. The record describes a pump in al-Jazari's book that is powered by flowing water, not by a person lifting a bucket. According to the TDV encyclopedia, the drive passes from the wheel to two gears, then to the rod and the arms of the pistons, and rotation becomes back-and-forth motion in the piston rods. The record stresses that the contribution is this arrangement, not the invention of lifting water. What is the input, and what is the output?

I can now

Notes

  1. 1. Ontario Ministry of Education, The Ontario Curriculum: Science
  2. 2. CEZERÎ, İsmâil b. Rezzâz — TDV (Sadettin Ökten), pp. 505–506
  3. 3. Al-Jazari — Donald Hill translation1974, pp.182–183
  4. 4. Al-Jazari — Donald Hill translation1974, pp.187–188
  5. 5. Al-Jazari — Donald Hill translation1974, p.188
  6. 6. Model of Double Piston Pump by al-Jazari — Science Museum Group, catalogue

The record page of this lesson

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