Mercury swivel commutator

Okay kiddo, let me explain what a mercury swivel commutator is. Imagine you have a toy train that needs power to move. The train needs electricity to run, but how do you give it electricity?
The same way, a mercury swivel commutator is a machine that helps to give electricity to some other machine.

It does this by using a metal called mercury. Have you ever seen mercury, it's actually like liquid silver and it's used in thermometers. In a mercury swivel commutator, there is a little cup that has mercury in it.

On top of this cup is a metal ring. And on this metal ring, there are little metal pieces that touch the cup containing mercury. These little metal pieces are like fingers. They touch the mercury in the cup as the metal ring moves.

As the metal ring rotates, one end of the machine gets electricity, and then the other end gets electricity. It's kind of like high-fiving someone as you pass by them.

So a mercury swivel commutator is a machine that helps give electricity to other machines. It does this using mercury and little metal fingers that touch the mercury as a metal ring rotates. Pretty cool, right?