"I'm ever so sorry, Bob," said Betty earnestly, "But--could you lend me twenty-five dollars?"

Bob whistled.

"I could," he admitted cautiously. "What's it for, Betsey?"

"That," said Betty, "is a secret."

Bob glanced at her sharply. His chin hardened.

"Come down here where we won't be interrupted," he said, leading the way to the wharf. "You'll have to give me a good reason for wanting the money, Betty."

CHAPTER XIX

BOB'S SOLUTION

"If you wanted twenty-five dollars and I had it," said Betty persuasively, "I'd give it to you without asking a solitary question."

Rob's lips twitched.

"But, Betty--" he began. Then--"Oh, do play fair," he urged. "You're younger than I am. Uncle d.i.c.k 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."

"But it's grown-up writing," protested Betty. "Though, come to think of it, we don't know any of the girls' handwriting," she added thoughtfully.

"What girl would be likely to do it?" asked Bob. "Can you recall a practical joker? This is copy book paper torn from an ordinary theme book. Yes, I'll bet a cookie a girl wrote it."

"Ada Nansen or Ruth Gladys Royal might do it to plague Libbie," said Betty slowly. "They don't like any of our crowd, and Libbie is so good at French she turns Ada green with envy. The more I think of it, the surer I am it is Ada. Ruth doesn't dislike any one actively enough to exert herself."

"Ada Nansen?" repeated Bob. "Isn't she that girl we saw on the train and who plumped herself down in my seat? I thought so--I remember you told me. Well, from the sidelight I have on her character, I believe she is the one at the bottom of this. That will explain, too, why you never catch any one digging up the bottle--she knows exactly when you are busy and when you are not."

"Bottle!" said Betty explosively, to Bob's amazement. "Oh, Bob! this morning Miss Jessup was talking to us about a.s.sociation of ideas, and she asked Ada what bee meant to her. We thought she'd say 'honey,' of course, but she said 'bottle.' Doesn't that show--"

"I should say it did!" Bob's voice was eager. "She took it for the letter 'B' and bottle was in her mind. You may depend upon it, that girl is at the back of all this fuss! Gee, when I've nothing else to do, I'm going to study up on this a.s.sociation of ideas stuff."

"You don't need it--you can get at things without a bit of trouble,"

Betty a.s.sured him affectionately.

"How will you go about pinning down Ada?" Bob asked anxiously.

"I'll cut out Latin to-morrow afternoon when she has a study period,"

planned Betty. "She'll think Libbie is reciting, and she'll not think of me at all, and I'll slip out and watch to see if she goes near the bottle. But what can I do if she does prove to be the right one? She'll tell Mrs. Eustice, and poor Libbie will be in a peck of trouble. I really think Mrs. Eustice would send her home if she knew."

"And serve Libbie right for being such an idiot!" p.r.o.nounced Bob severely. "However, I think she has been pretty thoroughly punished through fear. I only wish you'd told me this before, Betty, because I know exactly how you can deal with Ada."

"You do? Oh, Bob, what should I ever do without you!" cried Betty, forgetting that a few moments before she had berated him for his insistence. "Tell me, quick."

"Well, a crowd of us fellows happened to be over in Edentown last Friday night, and we saw Ada and Ruth at the movies," said Bob. "They didn't see us, for we sat back. They were the only girls from Shadyside, and Tommy and I decided they had sneaked out after dinner and walked all that distance. Now threatening isn't a very nice performance, Betty, but sometimes you have to meet like with like. I think, if when you see Ada digging up the bottle, you go to her and say that unless she returns the money and Libbie's first note to you and promises to let the matter drop--forever--you will expose her Edentown trip to Mrs. Eustice, she will listen to reason."

"So do I," agreed Betty. "I don't think she has touched the money--she has plenty. But I must have the note so that Libbie can destroy it. Mrs.

Eustice never lets us go to town at night, and I'm sure Ada and Ruth had to go down the fire-escape. Goodness, didn't they take a chance of being discovered!"

"Well, as I've already missed half an algebra recitation, and you know you have no business over here at this time of day, I move we begin our penance," suggested Bob. "Paddle home, Betsey, and if our hunch turns out wrong, we'll tackle another one."

"Oh, it won't--I'm sure you're right," said Betty gratefully. "Thank you ever so much, Bob. And the next time I'll tell you everything at the very first."

"Don't let me hear of another time," Bob called after her, with mock severity.

"Well, I never!" gasped Libbie, astonished, when Betty told her of Bob's suspicions. "Oh, Betty, wouldn't it be wonderful if it should be true!"

"I'm going to cut Latin this afternoon and find out," said Betty vigorously. "If Miss Sharpe asks for me, you don't know where I am; she never does anything but give you double lines to translate."

Betty knew that Ada had a study period, which she usually spent in her room, directly after lunch.

Directly after she left the dining room that noon Betty sped away to the foot of the hill. There were several stubby bushes about half-filled with wind-blown leaves and old rubbish and affording an excellent screen.

Betty crouched down behind one of these.

She had not long to wait. Ada, in her beautiful mink furs, which she clung to persistently, though the fall weather so far had been very mild, was presently seen coming across the gra.s.s. She walked straight to the spot where the bottle was buried, and, stooping down, brushed away the leaves and dirt. She lifted the bottle.

"Pshaw, it's empty!" she said aloud.

"Yes, it's empty," echoed Betty, stepping out from behind the bush. "And you are to give the money back to me, and Libbie's note with it."

"Is that so?" said Ada contemptuously. "I have something to say about that. I intend to see that that note reaches the proper person--Mrs. Eustice."

Betty took a step nearer, her dark eyes blazing.