To cross a stream, street or valley (where by the delay brought on by a flight of locks at possibly facet might be unacceptable) the valley can be spanned by a navigable aqueduct – a famed case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO https://cesarpvycg.full-design.com/considerations-to-know-about-urso-fofo-79499873