To cross a stream, street or valley (in which the hold off attributable to a flight of locks at either aspect will be unacceptable) the valley might be spanned by a navigable aqueduct – a renowned illustration in Wales could be the Pontcysyllte Aqueduct (now a UNESCO Planet Heritage https://musica-infantil64664.ezblogz.com/68683929/top-guidelines-of-urso-fofo