Dr. Raymond led the way into the house, through the hall, and down a long dark passage. He took a key from his pocket and opened a heavy door, and motioned Clarke into his laboratory. It had once been a billiard-room, and was lighted by a glass dome in the centre of the ceiling, whence there still shone a sad grey light on the figure of the doctor as he lit a lamp with a heavy shade and placed it on a table in the middle of the room.