To cross a stream, road or valley (exactly where the hold off because of a flight of locks at possibly aspect could be unacceptable) the valley can be spanned by a navigable aqueduct – a famous case in point in Wales could be the Pontcysyllte Aqueduct (now a UNESCO https://musica-infantil55432.goabroadblog.com/36128680/rumored-buzz-on-canal-infantil