To cross a stream, highway or valley (the place the delay a result of a flight of locks at both facet might be unacceptable) the valley may be spanned by a navigable aqueduct – a famed example in Wales is the Pontcysyllte Aqueduct (now a UNESCO Entire world Heritage https://johnnydnsyc.blogerus.com/58997332/the-best-side-of-urso-fofo