"Indeed and I will," promised Michael obediently, "but—what is it you are going to do, you two?"
They did not stop to explain, so great was their haste. They went clambering over the wall again, and tumbled down the other side upon the grass. The wind, from which they had been sheltered below, caught them again as they ran to the pool. They knelt down at opposite sides of the shallow curve and plunged their arms, shoulder deep, into the tossing water.
"I have found something," exclaimed Betsey almost immediately; "it feels like thin metal blades set in a ring."
She drew her prize, dripping, from the basin and held it up. As she sat back on her heels the wind loosened her hair and flung its dark mass over her shoulder. David, unable to see, took the object in his hand and felt of it carefully.
"That is certainly the missing valve," he pronounced, "so we know now that we are right. The other parts were two steel tubes, about as long as my hand. Those will not be so easy to find. They may have rolled away to the deep end."
No amount of fumbling on the bottom revealed anything further except that Betsey, lifting a stone, grasped a frog that was beneath it and almost tumbled into the water with the dreadful start its
