To cross a stream, road or valley (the place the delay attributable to a flight of locks at either facet could well be unacceptable) the valley is often spanned by a navigable aqueduct – a popular illustration in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Planet Heritage https://musicainfantil23222.mpeblog.com/65509413/everything-about-urso-fofo