To cross a stream, road or valley (where the delay caused by a flight of locks at possibly aspect can be unacceptable) the valley could be spanned by a navigable aqueduct – a well-known instance in Wales will be the Pontcysyllte Aqueduct (now a UNESCO World Heritage Web page) https://musica-infantil76554.ampblogs.com/the-smart-trick-of-musica-infantil-that-no-one-is-discussing-73825416