To cross a stream, highway or valley (wherever the hold off attributable to a flight of locks at both side would be unacceptable) the valley is usually spanned by a navigable aqueduct – a famed illustration in Wales may be the Pontcysyllte Aqueduct (now a UNESCO Globe Heritage Website) https://emilianoqxdhk.thechapblog.com/36178901/musica-infantil-for-dummies