After lunch Dorothy and Bill established themselves comfortably in the shade of the terrace awning back of the Bolton's house, and Dorothy's ground training began.

"First of all," said her instructor, "you must learn the signals for maneuvers, such as when the stick is shaken laterally, one hand held up, it means control of the plane is resumed by the instructor. Opening the throttle in a glide means resume level flight. There are eight of these signals to memorize. Then there are eight correction signals as well."

"I'll get them down soon enough," his pupil assured him. "Is that all?"

"I should say not. That's just a starter. Your ground training will consist of three parts: theoretic training, which takes up principles of flight; aircraft construction, aviation engine construction; and the elements of meteorology. Next, practical training, which embraces the maintenance and repair of aircraft together with maintenance and repair of aviation engines. Then comes aviation procedure, which takes up air commerce regulations; instruction procedure (signals come under that) and precautions and general instructions."

"Whew!" whistled Dorothy in dismay. "It is a business!"

Bill laughed at her forlorn expression. "Cheer up--the first hundred years are the hardest. But seriously, to become an efficient air pilot, it is essential to know thoroughly this ground work and all of the maneuvers I listed under elementary flying. None of them can be safely omitted. Of those I included under advanced flying, acrobatics are not required for a pilot's license, but they're a grand help in developing ability to handle a plane with confidence. Proficiency in reverse control flying, precision landings with power, forced landings and cross country flying is required for an interstate commercial license--and vital for every pilot."

"Is that all?" asked Dorothy, with diminished enthusiasm.

"No. To become a real flyer, you must understand aerial navigation and pass off formation flying and night flying. It sounds like a lot--but it really isn't so difficult. Of course, if you don't want to go the whole way--"

"Oh, but I do, Bill," she said earnestly. "It's only that I never dreamed there was so much to be learned. It kind of takes my breath away--"

"You mustn't let that bother you. I'm glad you're going to do the thing up right, though. It will take a lot of your time--but you'll find it worth your while. Let's get busy now. We'll start on signals. Then later this afternoon you can go up again if you feel like it."

For the next two weeks Dorothy worked daily with Bill. By the end of that time she had completed her elementary solo flying and was now engrossed in mastering the difficulties of reverse control.

Bill realized after giving her two or three lessons, that his pupil showed a high degree of aptitude for flying. Their trip home in the amphibian after the wreck of the Scud, had proved pretty conclusively to him that this sixteen-year-old girl had an unusually cool and stable temperament. Ordinarily, flight training is inadvisable for anyone under eighteen years of age, and Bill knew that twenty years is preferable. For, ordinarily, the instinctive coordination between sensory organs and muscles, which is necessary toward the control of a plane in the air, does not develop earlier. An airplane must be kept moving or it will fall; and the processes of reason are far too slow to keep up with the exigencies of flight. Flying cannot be figured out like a problem in mathematics. Calculation won't do the trick--there isn't enough time for it.

Of course there are exceptions to this rule. Bill Bolton was one himself, and Dorothy, he knew, was another.

When Mr. Dixon questioned him as to Dorothy's progress, he gave him a list of the maneuvers that had already been mastered, and the approximate length of time she had taken to satisfy him in performance.

"But that doesn't mean a thing to me--" objected the older man. "Look here--I was talking to a friend of mine who is an old Royal Flying Corps man. He said that Dorothy should wait several years before training. How about it? I know your reputation as a flyer, and I've proved my confidence in you by trusting you with my daughter's life. Why is it better for her to start now, rather than later?"

"Do you play the violin, sir?"

"No ear for music." Mr. Dixon shook his head in reminiscence. "My father played well. It was his ambition that we play duets together. But after wasting money for two years on lessons for me, he gave it up. My! the sounds I made when I practiced! It must have been torture to him. I can't tell one note from another--but I remember how awful it was. But what has that got to do with Dorothy's flying?"

"A good deal. You couldn't play the violin because you are not musical, and only a musical person can learn to play it well. In some respects, mastery of the violin and mastery of flying, have a common bond. With both the one fundamental requirement is natural or instinctive aptitude. Flying is an art, and without natural ability it is useless to attempt it. And if it isn't inherent, Mr. Dixon, it just can't be acquired. Moreover, the only way to find out if that aptitude exists, is by trial. If Dorothy had the natural ability for the violin that she has for flying, practice and experience would make her a second Kreisler!"

A smile crept along the corners of Mr. Dixon's mouth. "Ah, but Kreisler is a man!"

"I know, sir, but honestly, sex has nothing to do with it."

"So you think she should keep on with her flight training?"

"I know she should, Mr. Dixon, if you want her to fly at all. She has all the qualifications that go toward making a really good air pilot."

"Well, I'm glad to hear you say it, and glad you're so enthusiastic."

"Of course I am," declared Bill. "She's fearless and alert and she loves the work--she'll do well."

And so Dorothy continued her flight training.

She came down one afternoon from a solo flight and Bill, who had been watching her maneuvers from the shade of the hangar, walked over as the plane rolled to a stop.

"Not so good--" she called out as she sprang to the ground. "I nearly overshot my landing."

"So I noticed," returned her young instructor rather grimly. "Carelessness, you know, that's all. Keep your mind on the job. And here's something else. Remember, when you are making a flipper turn, the nose must first be dropped to level. Otherwise you'll get into serious trouble. Also don't forget that until the wings pass an angle of bank of 45 degrees your controls are not inverted and must be handled as in a normal turn."

"O.K. skipper," she sighed. "I'll remember in future."

"One thing more. Those two 360-degree spirals with an altitude loss of about 1000 feet were well done. But you must bring your plane out of reverse control spirals above 1500 feet altitude--Now we'll put your bus away and call it a day."

Work finished, they strolled over to the terrace where Frank as usual had iced drinks awaiting them.

"You've certainly taught me a lot in fourteen days," observed Dorothy after sipping her ginger ale. "But it's kind of put a crimp into our detective work. By the way, you never have told me what you had up your sleeve with regard to the robbery--something to do with an airplane coming in handy, wasn't it?"

"Your memory is better on the ground than in the air!"

"Pish! likewise, tush! You don't intend to wait till I finish training or anything like that, before coming across with that clue that will help us land those birds in jail?"

"Why should I?"

"I don't know. Thought maybe you might figure my interest in landing the gang would take my mind off flying--"

Bill took a long, refreshing drink of the iced liquid at his elbow. "You're on the wrong track. I'm simply biding my time and keeping a finger on the pulse of the robbery, as it were."

"Do you mean that?"

"I'm in deadly earnest," he assured her, although his eyes twinkled mischievously.

"Then all I can say," exclaimed Dorothy, "is that you're one up on everybody else who is working on the case."

"How come?"

"Why? you know as well as I do that when the Packard rolled out of the alley by the bank, in all probability carrying three people and the loot, it disappeared completely. And it's stayed that way ever since, hasn't it? That's two weeks ago tonight."

"Any new clues lately?"

"Nary a one. The police traced the red-headed girl's finger prints to Sarah Martinelli, better known as Staten Island Sadie. They sent Dad her record--I saw it--believe me, that lady is a ripe egg!"

"How beautifully expressive."

Dorothy raised her eyes from her compact's tiny mirror.

"Well, she must be!--Are you trying to kid me?"

Bill finished his ginger ale. "Come on, tell me the rest."

Dorothy grinned. "That's all there is, there isn't any more, my child. Don't imagine those police are efficient, do you? None of the missing bonds have been found, and as for the money, those chaps have probably spent it by this time. I feel awfully sorry for Daddy, though," she continued in a changed voice, "--that Mrs. Hamberfield is still raising the roof about her diamond necklace. Serves her right for being such a mutt, I say."

"Tough on both parties, I should think."

"Nothing of the kind. Daddy says that her husband, Stonington Hamberfield, made his coin profiteering during the war. What do you think his name really is?"

"You tell me."

"Steinburg Hammerfeld--isn't that a hot one?"

"A Hun, eh?"

"Well, if he isn't--I'm President Hindenburg, San Francisco Harbor and the Statue of Liberty all in one!"

Bill smiled appreciatively at this sally, then changed the subject. "Let's go to the movies this evening?"

"Can't. It's Pen and Pencil Club night."

"What on earth is that?"

"Oh, about a year ago, a bunch of us at high school, girls and fellows, started a club to write short stories. We meet every other Tuesday night at some member's house. Everybody has to write a story at least one a month, or they're fined a quarter. We read aloud and discuss them at the meeting. Come with me after supper and pay my quarter."

"Nothing doing. That kind of thing is my idea of a perfectly terrible evening."

Dorothy slipped the compact into a pocket of her jodhpurs and got to her feet.

"That's where you're all wrong, Bill. Noel Sainsbury, the writer, is our adviser. He makes it awfully interesting--we have lots of fun. He was a naval aviator during the war. You two should have lots in common. Do come along and meet him."

"Why I dined at his place, Little Windows, last night!"

"Oh, you do know him?"

"Naturally. Where would I be if it weren't for him? Look at the books he's written about me. Noel Sainsbury brought Dad and me to New Canaan. We're awfully fond of him and his wife and little girl."

"Yes, Winks is a darling and Mrs. Sainsbury is a peach--" Dorothy agreed. "She comes to our meetings, too. I'm named for her, you know."

"Really? That's interesting."

"You bet. Then you'll come tonight?"

"I'd like to, very much."

"All right. The meeting is at Betty Mayo's, in White Oak Shade. I'll be here about eight in my car and drive you down there."

"I'll be ready--so long!"

"So long!"

It was nearly quarter to nine before they got started, as things turned out. Mr. Dixon had gone to New York for the day on business, had been detained in town, and Dorothy waited dinner for him.

"Well, we won't have missed much," she explained to Bill as her car breasted the Marvin Ridge Road. "The first half hour is always taken up with the minutes of the last meeting and all that parliamentary stuff. I love driving in the twilight, anyway. Next place on the left is where we're bound. We'll be there in a jiffy."

They rounded a bend and came upon a Packard parked at the roadside. The hood was up and a man looked up from tinkering with the engine as their lights outlined his figure.

"Pull up! pull up!" Bill's tense whisper sounded in her ears. "Where are your eyes, girl?"

But Dorothy needed no second warning. She shot home the brake, for she too had seen the great, misshapen boot that the dapper little motorist wore on his left foot.