At half past four, Mr Williams was at home again Suddenly, somebody knocked on his door. Mr Williams opened it. A tall, thin man was standing there. "Hello, Binks," said Mr Williams. Hello, Williams," said the man. "Are you working?' "No, no. Come in. Come in,' said Mr Williams. "I'm going to have some tea soon Professor Binks was a scientist. He lived in Canterbury College too. He came into the room and he sat at the table. The sky was dark outside the window. Mr Williams lit the lamps in the room. Then he closed the curtains. Professor Binks picked up the engraving What's this, Williams?" asked. 'Are you going to buy it for the museum? How did the artist make it? It's an engraving, Binks,' replied Mr Williams.