"Mister Geoffrey, my experiment shows that the dynamo and the bulb are both working properly, I said. So why won't the radio play?I don't know, he said. Try connecting them here.He was pointing toward a socket on the radio labeled AC, and when I shoved the wires inside, the radio came to life. We shouted with excitement. As I pedaled the bicycle, I could hear the great Billy Kaunda playing his happy music on Radio Two, and that made Geoffrey start to dance.Keep pedaling, he said. That's it, just keep pedaling.Hey, I want to dance, too.You'll have to wait your turn.Without realizing it, I'd just discovered the difference between alternating and direct current. Of course, I wouldn't know what this meant until much later.After a few minutes of pedaling this upside-down bike by hand, my arm grew tired and the radio slowly died. So I began thinking, What can do the pedaling for us so Geoffrey and I can dance?"