chemical battery
"A chemical battery is like one full bucket and one empty bucket. Pour the water from the full bucket through the tube into the empty bucket, and you have current until the full bucket runs out.
Electromagnetic induction is like a closed loop of tube filled with water, with a motor-driven propeller inside. Turn on the propeller, and the water will flow around and around as long as you can supply power to the propeller."
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.