In 1778, the Cann Slate Quarry was owned by John Parker, and in order to make transport of the slate easier, he asked the engineer John Smeaton to survey a canal, to run from the quarry to the bridge at Marsh Mills. The River Plym between the bridge and Plymouth was navigable by barges. Although Smeaton carried out the work, he concluded that the canal, which would be long and would need several locks to accommodate the drop of in level, was unlikely to be economic, since the only trade would be the output from the quarry. He therefore suggested that a tramway would be a better solution, and could be built for about half the cost of the canal. Parker did not proceed with either option.