In the center of the chamber stood a grim, black altar; it had been rubbed all over with a sort of phosphorous, so that it glowed dully, lending a semi-illumination to the shadowy cavern. Towering behind it on a pedestal of human skulls, lay a cryptic black object, carven with mysterious hieroglyphics. The Black Stone! The ancient, ancient Stone before which, the Britons said, the Children of the Night bowed in gruesome worship, and whose origin was lost in the black mists of a hideously distant past. Once, legend said, it had stood in that grim circle of monoliths called Stonehenge, before its votaries had been driven like chaff before the bows of the Picts.