Graves had used in speaking to the housekeeper. Apparently it was a Christian name of some kind; but why did Mr. Graves call the woman by her Christian name when Mr. Weiss addressed her formally as Mrs. Schallibaum? And, as to the woman herself: what was the meaning of that curious disappearing squint? Physically it presented no mystery. The woman had an ordinary divergent squint, and, like many people, who suffer from this displacement, could, by a strong muscular effort, bring the eyes temporarily into their normal parallel position. I had detected the displacement when she had tried to maintain the effort too long, and the muscular control had given way. But why had she done it? Was it only feminine vanity—mere sensitiveness respecting a slight personal disfigurement? It might be so; or there might be some further motive. It was impossible to say.
Turning this question over, I suddenly remembered the peculiarity of Mr. Weiss's spectacles. And here I met with a real poser. I had certainly seen through those spectacles as clearly as if they had been plain window-glass; and they had certainly given an inverted reflection of the candle-flame like that thrown from the surface of a concave lens. Now they obviously could not be both flat and concave; but yet they had the properties peculiar to both flatness and concavity. And there was a further difficulty. If I could see objects unaltered through them, so could Mr. Weiss. But the function of spectacles is to
