"But, Betty—" he began. Then—"Oh, do play fair," he urged. "You're younger than I am. Uncle Dick expects me to look after you. Goodness knows I don't want to pry into your affairs, but when you borrow fifteen dollars and then want twenty-five the same week, what's a fellow to think? If some one is borrowing from you, it's time to call a halt; you're not fair to yourself."
Betty looked startled. How could Bob possibly guess so near the truth? She began to think that the better part of wisdom was to confide in this keen young man.
"Come on, Betty, tell me what you want it for, and you shall have twice twenty-five," said Bob earnestly. "I've most of my allowance in the school bank. It's all yours, if you'll let me have an inkling of the reason you need money."
"Well," said Betty, slowly, "I didn't promise I wouldn't tell—only that I wouldn't tell Bobby or Mrs. Eustice. It's Libbie who has to have the money."
She sketched Libbie's story for him rapidly, Bob listening in silence. At the end he asked a single question.
"Have you any of those notes asking for money?"
"Here's one." Betty thrust her hand into the pocket of her sweater and pulled out the crumpled paper that Libbie had shaken out of the bottle that morning.
"Were they all written on this same kind of paper?" asked Bob, reading the note.
"Ye-s, that is, I think so," hesitated Betty. "I really haven't noticed. Why?"
"Because I don't think any man wrote this," announced Bob confidently. "I think some girl at school has done it, either as a joke or to torment Libbie."