At the boys’ excited exclamations Mr. Henderson, who had been examining a picture, turned to them.
“What’s all the excitement, boys?” he asked. “Anything interesting that Rawlins has found?”
“Well I should say so!” declared Tom. “Look, here’s some of those Rochelle salt crystals and a resonance coil. Do you know about them, Mr. Henderson?”
“Jove, you’re right!” ejaculated the other. “Yes, I’ve seen experiments made with the salt—and have seen them used in submarine work during the war too, and I’ve read Gen. Squiers’ articles on the resonance coil and its properties. No wonder those fellows in the sub got by with such things to aid them.”
“Well I suppose it’s all mighty plain to you, but I’ll be hanged if I can see where Rochelle salts come in,” declared Rawlins. “I thought that was medicine.”
“So it is, under certain conditions,” agreed Mr. Henderson, “but if the salt is prepared or ‘grown’ so as to form a certain kind of crystal it possesses almost magical properties. By its aid one can hear a fly walk, insects talk or molecules of metal turning over in an iron bar.”
“Nothing doing!” exclaimed Rawlins. “I can believe pretty big yarns after seeing what radio does, but I’m from Missouri when you talk about a bit of salt making a fellow hear a fly’s trotters or the inside of iron getting restless. You’ll have to show me.”
“That will be easy, I imagine,” replied Mr. Henderson. “Tom says he’s been reading the accounts of it. I expect he can make you hear your own thoughts almost. But with no exaggeration it is a most marvelous thing. During the war we used it as a detector to hear vessels at a distance—particularly subs, and it saved countless thousands of lives. One man in Washington is employed to devote all of his spare time merely to growing these special crystals. If Tom can arrange the apparatus on the submarine we can locate the other sub if we get near her. You’ve made a great find, Rawlins.”
“What’s that you said about another sub?” asked Rawlins. “Don’t tell me they’ve got another one!”
“That’s what we think,” replied Mr. Pauling. “I forgot you didn’t know.” In a few words he related Commander West’s story of the finding of the deserted schooner and the disappearance of the crew.