“It must have been Mr. Reynolds’ workshop,” she suggested, “and see, even those steel bars are melted together. The fire must surely have been hottest just here.” “I believe you’re right.” David was picking his way about looking at the broken engine parts and the melted bits of steel. “I suppose he was working even then on that same invention. I think it ought to be a very great thing when it is done.” “I think,” began Betsey, “that—oh, look, look!” She stood transfixed with dismay, staring at something behind him. David gave one glance and knew better than to pause and look again. “Quick,” he cried, and, seizing her hand, dragged her, almost headlong, across the open space and up another slope of sliding bricks. The old chimney, split by the lightning and weakened by fire and frost, was ready to tumble at the slightest shock and had received its final impetus from the collapse of the neighboring wall. As Betsey looked at it the whole mass was tottering and, but for David’s quickness, would have engulfed them both. As it was they were nearly smothered by the cloud of dust and crumbled mortar. Blinded and breathless, they scrambled out of the hollow to safety. David’s dusty face had not lost its cheerful smile, but he spoke with great decision. “I was very wrong to let you go in there,” he said. “I might have seen that the whole place is shaky and that the walls have been collapsing, little by little, for years. We will not go near this end of it at least, again.” Elizabeth knelt by the pool to wash the dust from her face and hands, while David, having done the same, went to fetch his geometry book. “Now,” he said, sitting down by her with something of a sigh, “we really must, I suppose, begin on that tiresome pyramid.” They had a gay session there under the trees before the light began to fail, while each, by instructing the other, succeeded in mastering all former difficulties. In the end they fell to firing rapid questions at each other, Betsey trying to trip David in his fluent statement of the theorem, he in turn lying in wait for her on obscure points of the proof, until neither could be shaken from the thoroughness with which knowledge was now entrenched. “How lucky it is,” said Betsey, putting down the book and leaning back with her elbow on the rim of the pool, “that each of us stuck in a different place! I hope it will often be that way and that we can help each other more. Now why—” her method of finding things out was apt to be by blunt questioning, a habit she could not easily put aside, “why are you getting ready for college all alone when it is so much easier to do it by going to school?” David stretched his long legs in the grass and looked fixedly down into the water.