We went on, deeper and deeper into the earth. Finally we arrived at a vault in which the air was so old and heavy that our lights almost died. Against three of the walls there were piles of bones higher than our heads. From the fourth wall someone had pulled down all the bones, and they were spread all around us on the ground. In the middle of the wall was an opening into another vault, if I can call it that — a little room about three feet wide, six or seven feet high, and perhaps four feet deep. It was hardly more than a hole in the wall.