To cross a stream, road or valley (where by the delay because of a flight of locks at both facet could well be unacceptable) the valley might be spanned by a navigable aqueduct – a popular illustration in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Entire world https://musica-infantil66544.fitnell.com/77925703/urso-fofo-can-be-fun-for-anyone