“Electricity - clean simplicity” so the advertisement goes. Actually, it’s not so simple when you try to explain exactly what it is, and you have to hand it to the dedication of the 19th-century pioneers who wrestled to tame this natural force. Some went to great pains, like the scientist who stuck an electrode into the fresh cavity in his own mouth after a tooth extractionI ouch! But electricity changed the world; we could even clean up legal exection thanks to the bright sparks who dreamed up Old Sparky (page 8).