The well sweep saves effort by using the principle of the lever.
Tips
history
Mentioned in 《庄子·天地》: an old man refuses to use a 桔槔, saying machines breed scheming hearts (有机械者必有机事，有机事者必有机心) — an early Daoist meditation on labor-saving technology.
memory
Picture a long pole pivoted on a forked post: rope and bucket on one end, heavy stone on the other. Push down to fill, let the counterweight haul the water back up. The English term 'shadoof' (Egyptian/Arabic origin) describes the same device.
