To cross a stream, road or valley (where the hold off because of a flight of locks at possibly aspect might be unacceptable) the valley can be spanned by a navigable aqueduct – a famous case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO Earth https://urso-fofo63837.bloginwi.com/70745902/considerations-to-know-about-canal-infantil