…electron. And so it goes for a very long distance, a most amazing thing. In fact, it's so amazing that Mr. Gaus and Weber, who first built some of these galvanometers, I don't remember the city in Germany, but they connected a long wire to see how…

…make it go. And they came all the way across the city. And Mr. Gauss would close a switch on the battery. And Mr. Weber would watch the movement of the galvanometer. And that was the first telegraph. You can imagine the excitement of the days when they…

…the MKS system, and it's 3 times 10 to the eighth. Just for your interest, the MKS unit of magnetic field is called a Weber per square meter. There's an older unit which is still being used in words. You see it everywhere. It's called a Gauss, and…