The superiority of its grinding facilities largely explains Sheffield's triumph over its rivals as the place where cutlery and edge tools were made. The local sandstone was ideal for grinding and the rivers and streams fell quickly off the Pennines and could be dammed at frequent intervals. Grinding was a specialist craft in the production of scythes by the 16th century but not in the cutlery trades until the 18th century. With the introduction of factories and workshops driven by steam power in the 19th century grinding became a notoriously unhealthy occupation; grinders were well paid but died young of a form of silicosis, or ‘grinders’ asthma’. See David Crossley (ed.), Water Power on the Sheffield Rivers (2nd edn, 2007).