The official kilogram, a cylinder of platinum and iridium maintained by the International Bureau of Weights and Measures, is more than 130 years old... Some scientists now believe the official kilogram may be losing mass...As my source for the story puts it, "An honest imperial pound would never show such inconstancy."
And what happened to all that wonderful rationality of the meter being derived from some well-rounded fraction of the earth's dimensions?
Over the years, the official meter has been redefined several times and is now “the length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 of a second.”Gone the way of Brumaire, Pluviôse, Fructidor and hopes of guillotines in Piccadilly Square, I suppose. Mustn't be unkind, though, they're only poor Parley-Voos after all.