I remember one evening on the Tamar [river in South-west England]; the sun had set, and the shadows become very deep. Demaria, looking at a seventy-four [ship] lying under Saltash in Cornwall, said, 'You were right, Mr. Turner; the ports cannot be seen. The ship is one dark mass'. 'I told you so', said Turner: 'now you see it all is one mass of shade'. 'Yes, I see that is the truth, and yet the ports are there'. [Turner:] 'We can take only what we see, no matter what is there. There are people in the ship: we don't see them through the planks'. 'True', replied Demaria. There had been a discussion on the subject before between the two professional men, in which Turner had rightly observed that after sunset, under the hills, the port-holes were undiscernible. We now had ocular proof of it.