> > In addition, the metric system derives some units from more basic ones. A > second is the period of a pendulum that is one metre long. >
Are you sure about that? I know that originally the metre was defined as 1 millionth (or ten millionth?) of the distance from the equator to the north pole running through Paris. The definition of the second wasn't changed AFAIK. The have both subsequently been redefined more accurately and to make them more convenient to measure in a laboratory. But if, as you say, a second and a metre are related that way it would have to be an incredible coincidence. Rod
