I have been describing the historical development of the metric system
to my students this week. One thing has always bothered me. Perhaps
someone can provided some insight.
Why was the definition of a kilogram changed from the mass of one
deciliter of water 4 C to the mass of the prototype in France? It seems
to me that the mass of water would have the advantage of being portable
and offer a definition of similar precision to that given for the
meter. What am I not considering?