To cross a stream, road or valley (in which the delay brought on by a flight of locks at either facet could well be unacceptable) the valley is usually spanned by a navigable aqueduct – a famed illustration in Wales could be the Pontcysyllte Aqueduct (now a UNESCO Earth https://comprarinstagramviewsreel78876.mybuzzblog.com/16996494/canal-infantil-fundamentals-explained