 By the end of the 18th century, the trail of pack horses across the rugged terrain was too much, and in 1817 the 4.5-mile-long Tavistock Canal was opened.The canal included a 1.5-mile tunnel which ended 237 feet above the quay at Morwellham.From here an inclined plane was constructed to bring the iron barges down to the quay, powered by a water wheel.