Davis was looking at her, paying but little attention to what she was saying, simply absorbed in looking. Gerrod saw his expression. "Don't you _ever_ use your head?" he demanded. "Here you are worrying about Nita's father, and there you have a reward offered that would clear away all his objections at once." "Why--why, that's an idea!" said Davis. "Glad you think so," said Gerrod acridly. "Suppose you two talk things over. You have a brain, Davis, even if you rarely use it." Davis laughed good-naturedly. After dinner Evelyn and her husband retired to the laboratory again. Neither of them wanted to waste any time that might be useful in developing a means of fighting the Silver Menace. They were deep in their work when Davis and Nita rushed in upon them. "We've got it!" said Davis dramatically. Nita was clinging to his arm, and looked immensely proud of him. "What have you?" asked Gerrod practically. "A way to clear off the Silver Menace," said Davis. "You know the animalcules have very fragile little shells. In the war we had to fight submarines with armored shells. We got the subs with depth bombs dropped near them. The concussion smashed them up. Now let's take bombs and drop them in the silver sea. The concussion will wreck the little shells for miles around." Gerrod thought the idea, over carefully. "It might turn the trick," he said thoughtfully. Davis beamed. "We'll try it at once," he said enthusiastically. "Or, rather, we'll start first thing in the morning. We must have light to experiment by. I'll phone the aviation field at once to have the big plane ready." "I'm going, too," said Nita determinedly. "We'll all go," said Davis expansively. The plane left the ground shortly after daybreak. It was a curious sight to see the absolutely cloudless sunrise. The sky paled to the east, then glowed fiercely red, lightened to orange and the sun rolled up above the horizon. The big airship circled grandly until it had reached a height of nearly ten thousand feet, then swung for the east and sped away. Nita sat in the seat beside the pilot, her face flushed with excitement. Gerrod and Evelyn occupied seats farther back, and the single engineer leaned against the rear of the car, where he could keep both ears open to the roar of his engines. The twin bomb racks along the outside of the car were filled with long, pear-shaped, high-explosive missiles, and the electric releasing switches were close beside Davis' hand. A case of hand grenades was carefully packed in the car, too.