"What is the average size of a picture?" she asked. "Perhaps two feet by two and a half," she said. Castalia made notes while Helen spoke, and when she had done, and we were trying not to meet each other's eyes, rose and said, "At your wish I spent last week at Oxbridge, disguised as a charwoman. I thus had access to the rooms of several Professors and will now attempt to give you some idea--only," she broke off, "I can't think how to do it.