To cross a stream, street or valley (where the delay because of a flight of locks at possibly facet can be unacceptable) the valley could be spanned by a navigable aqueduct – a famed case in point in Wales is the Pontcysyllte Aqueduct (now a UNESCO World Heritage Site) https://comprarinstagramviewsreel78876.mybuzzblog.com/16996494/canal-infantil-fundamentals-explained