To cross a stream, street or valley (in which the delay caused by a flight of locks at possibly aspect might be unacceptable) the valley might be spanned by a navigable aqueduct – a well-known example in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO Earth Heritage Internet https://musicainfantil83692.blogars.com/35910076/urso-fofo-things-to-know-before-you-buy