To cross a stream, road or valley (where the hold off because of a flight of locks at both side could be unacceptable) the valley could be spanned by a navigable aqueduct – a well-known example in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage Website) https://musica-infantil12210.bluxeblog.com/69255425/considerations-to-know-about-urso-fofo