The redefinition of the kilogram takes effect in two weeks time. To mark the event, Martin Vlietstra, one of our frequent contributors, looks at the “old” and “new” versions of this international standard.
We reported a few weeks ago on the redefinition of the kilogram. In this article, Martin Vlietstra, one of our regular contributors, outlines Britain’s contribution to the creation of the prototype kilogram upon which the definition had relied since 1889.
After the controversy of recent weeks with bashed bridges, furlongs and novel signs, we turn to something deadly dull – the definitions of length, mass (or weight) and capacity (or volume) and their relationships.