Where does a machine's energy come from?

This lesson asks you to describe a variety of energy transfers and transformations and to explain them with the law of conservation of energy. The museum offers machines of the Islamic world that raised water, with what their records say about what drove them. The law itself and the calculations are for your class to bring. ¹

Look at the expectation: it asks for transfers and transformations. For a machine, ask what goes in, what moves and what comes out, and whether any part only looks like the source of the motion.

Follow the energy through one machine from Taqi al-Din's book. In Al-Turuq al-saniyya, Taqi al-Din ibn Maruf described six tubes with pistons, weights and valves, actuated by projections distributed around a shaft and connected to a shared outlet ². Rising and falling strokes perform different functions: a cam raises a piston through a rocker; a weight then drives it downward ³. An inlet valve and a delivery valve distinguish admission from discharge ³. Their common pipe collects delivery; it does not become an independent energy source ³. Ask which part gives the piston its rise, which gives it its fall, and which only directs the water. The record is the six-cylinder pump.

The records preserve no statement by al-Jazari of why he hid the drive of his lifter. Hill infers from its materials and ornament that its purpose was at least partly decorative, rather than solely a large practical plant ⁴. The text itself pairs useful transport with deliberate beauty: silk, copper, marble and colour ⁵. For Taqi al-Din no sentence of his own is preserved either; the record reads the intention of this design as successive delivery rather than only one piston's pulse ².

A figure that moves is easy to take for the source of motion. In the hidden-drive lifter the cow is hollow wood, carried by a lever with its hooves clear of the platform, and water drives the machine ⁵. Discharged water turns a wheel in a lower chamber, and gears carry the rotation to a vertical shaft ⁵. The shaft turns the cow, not the reverse ⁶.

These are machines on paper. Hill's explanatory drawing enlarges the jars and shows only two for clarity, and he notes a pictured overflow pipe that the wording does not mention and another machine, mentioned but not described ⁴. No working original or measured power is reported for the lifter. For Taqi al-Din's pump, the modern engineering study explicitly lacks evidence of historical manufacture and assumes many model dimensions ⁷. Ask what each source could tell you about energy, and what it never measured.

Choose one part that catches the eye in one of these machines. Is it a source of energy, a part that transmits it, or a load that the machine carries? Which record sentence would you point to, and what would someone who reads the machine differently say against you?

• Al-Jazari's hidden-drive water lifter: the pool, the jars and the wooden cow.
• Al-Jazari's animal-powered scoop lifter: an animal supplies the motion; gears and a pin in a slot do the rest.
• Taqi al-Din's six-cylinder pump: six pistons, cams, weights and valves.
• Taqi al-Din ibn Maruf: the author of the book that describes the pump.

Read the records of al-Jazari's hidden-drive water lifter and Taqi al-Din's six-cylinder pump. For each, draw boxes and arrows from the source of energy to the lifted water, and mark any part that looks like a source but is not.