To cross a stream, road or valley (where by the delay caused by a flight of locks at possibly side would be unacceptable) the valley is usually spanned by a navigable aqueduct – a famous case in point in Wales is definitely the Pontcysyllte Aqueduct (now a UNESCO Earth https://preliminar-cayo-perico-gt32975.blog-eye.com/37353252/5-easy-facts-about-musica-infantil-described