"Professor!" cried the Director, rushing to meet their guest and lecturer as the door was thrown open, and the great man appeared, calm and composed, as if there was nothing more in the wind than an ordinary Scientific Discourse. "You are always welcome, my friend, always welcome"—the two enthusiasts for science wrung hands—"and never more welcome than to-night. Then the great mystery is to be solved at last. The Theatre is crammed with people. What does it mean? You must tell me before you go in."