literally a cup of water to put out a burning cart of firewood; describes a tiny effort or amount that is useless against a huge problem

A vehicle equipped with a water tank and spraying device used for washing roads, controlling dust, or watering plants

a waterwheel powered by the wind; wind-driven irrigation wheel

A traditional Chinese wooden irrigation pump or waterwheel consisting of a wooden chain with paddles that move through a trough; it is powered by humans or animals and named for the chain's resemblance to a dragon's spine.