| http://www.w3.org/ns/prov#value | - As Europe and the United States entered the industrial revolution not only did rising prosperity increase demand for such items as ivory combs, cutlery handles, and ornaments, the invention of new machinery made possible completely new mass-produced products such as piano keys and billiard balls (both required vast amounts of ivory, as each keyboard needed a pound and a half of ivory while billiar
|
