It was the remembrance that uninterrupted effort would fatigue them to a point where their strength would be taxed beyond recovery which made Aylmer at last call a halt. They went and sat beside the sleeping child. To economize the light, they extinguished the lamp. And then--they rubbed their eyes. A tiny beam of light, dim, faint, gray but distinguishable, was filtered down into their prison at the point where one of the cloister pillars reached an arch. It fell upon the flags in a little circle. Aylmer reached it in two strides. He gave an exclamation. "It is a pipe from the spouting of the roof," he cried. "I see the sky. I see the sky!" She was at his side in an instant. In her turn she looked up into the hollow of the tube, to see light. She gave a little gasp. "It's wonderful--wonderful!" she breathed. "Only that little way up--ten feet, twelve, perhaps, and freedom. And we are here!" "It means two things of infinite importance!" he rejoined. "Air and, in all probability, water. If the gutter which discharges into this is still intact, we shall receive the rain when it comes. And after earthquake it comes, invariably." She was not paying him attention. Her eye was still fixed below the tiny opening; she continued to look up as if the tiny disc of brightness fascinated her, as if she would drink draughts of the outer air thus delivered to them as if from an immense cistern. And then the emotion of sudden discovery illuminated her face. "We can signal!" she cried. "We can attract attention! We have only to thrust a rod up through that, and it will tell our tale. Surely there are rescuers at work by now; a whole city cannot be left to its fate!" His eyes glistened. "God sent that thought to you--God himself!" he cried. "We must have a rod; we must make one!" He turned and re-lit the lantern. He examined the splintered woodwork of the boat with a calculating eye. Wood was at their service in plenty, but the tools to deal with it were wanting. Neither of them possessed a knife. He searched the pockets of the dead, but had no success. For a moment they stood regarding each other in incredulous despair. Surely Fate, after bracing them with this hope, was not going to torture them by withdrawal? And then Aylmer's eye fell upon the baling slipper. He lifted it with a gesture of relief; he tore the strip of tin from off it and held it up. "That is our blade!" he cried. "We have only to pare down splinters till they will pass through the pipe, and the thing is done." He picked up a piece of planking as he spoke, worked the metal into the grain till a split began to gape, and then, wrapping a piece of tarpaulin round each end of his impromptu blade, worked it to and fro and downwards. A thin sliver of wood was the result--one about eighteen inches long.