Comparison of the imperial and US customary measurement systems metre, as 1852 metres. Traditionally, both Britain and the US used three different weight systems: troy weight for precious metals, avoirdupois weight for most other purposes and apothecaries' weight for medicines. However, apothecaries' weight has now been superseded by the metric system. One important difference is the widespread use in Britain of the stone of 14 pounds () for body weight. This unit is not used in the United States, although its influence was seen in the practice, until World War II, of selling flour by a barrel of 196 pounds (14 stone). Another difference arose when Britain abolished the
Hierarchy of precious substances Hierarchy of precious substances In popular culture, sets of precious substances may form hierarchies which express conventional perceived relative value or merit. Precious metals appear prominently in such hierarchies, but as they grow, gems and semi-precious materials may be introduced as part of the system. The sequences can provide interesting examples of the arbitrariness of semiotic signs. Jubilees have a hierarchy of years: silver (25 years), ruby (40 years), golden (50 years), diamond (60 years), and platinum (70 years). Wedding anniversaries extend the jubilee hierarchy with various sequences of substances filling in many of the gaps between the same major