After their exciting day, the next two weeks proved more than dull to the youthful members of the Sky Patrol.

Nothing happened to clear up the mystery.

To the surprise of the yacht crew, Captain Parks kept them all busy preparing, the day after Mrs. Everdail’s dramatic discovery, for a run to Bar Harbor, Maine.

That was unusual. After a trip across the Atlantic, the yacht was ordinarily laid up for awhile, giving its crew some shore liberty.

Captain Parks, however, agreed with Mr. Everdail, who trusted him absolutely—if Sandy did not—that it would be wise not to give any person who had been on the yacht during its crossing any chance to get away.

“On the run,” Mr. Everdail told Sandy and Dick, “and while we lay over at Bar Harbor, you two can watch for anything suspicious. My wife won’t let me say that Mimi, the maid, could be guilty—besides, how could she get into Captain Parks’ safe?”
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“I think, myself, some man of the crew would be the one to watch,” Dick agreed. “Maybe the steward, who could have a reason for getting into the captain’s quarters.”

“But it was a woman Larry saw, through the glasses, at the stern,” Sandy objected.

“Well, then—there’s the stewardess who attends to the ladies’ cabins,” argued Dick. “We can watch her.”

They did, but no one on board asked for shore leave, either on the day before lifting anchor or during the stay in the Maine waters. Dick and Sandy used ears and eyes alertly; but nothing suspicious looking rewarded their vigilance.

Larry, staying at the old estate home with Jeff, had some compensation, at least, for being separated from his chums. Not only could he keep an eye on things and be ready if Jeff called for an aide; as well, he had his daily instruction in ground school and in the air.

Already “well up” on all that books could tell about engines, types of airplanes, construction methods, rigging and even handling a craft in the air, he got the practical personal experience that is the only real teacher, and the thrill of donning the Gossport helmet, with its ear ’phones and speaking tube through which Jeff, in the second place of the amphibian or the airplane, instructed him, correcting faults or gave hints, was a real thrill.
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He learned, first of all, not to start up an engine while the tail of the ship pointed toward a hangar, or other open building, or toward a crowd, in future, on a field.

The propeller blast threw a torrent of dust and as Jeff told him, he mustn’t become that most unpopular of airport nuisances, a “dusting pilot,” whose carelessness flung damaging clouds on airplanes in hangars and people on the fields.

Learning to warm up the engine, to check up on instruments, to keep the ship level while taxiing down the field to head into the wind, to make the turn, either in stiff wind or gentle breeze, so that the wind did not tip the craft and scrape wingtips—these and a dozen other things he acquired in several early lessons.

The second place of the airplane had been fitted with a set of dual controls, rudder bar, throttle and “joystick” so that Jeff, for two successive hops, let Larry put feet on his rudder bar and lightly hold the stick as Jeff manipulated the controls and explained, by use of the Gossport helmet, why he did this or that.
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Jeff believed, as does every good instructor, that showing, and explaining, is necessary as a first step, but that a flyer is developed only by practice during which he makes mistakes and is told why they are mistakes and how to correct them, thus gaining confidence and assurance by actually flying.

“That-there time,” Jeff might say, “when the caretaker ‘playing mechanic’ and pulling down the prop till the engine catches, didn’t you open up the throttle too wide? Better to open it just enough to give the engine gas to carry along on—and even cut the gun a bit more to let it run fairly slow till it warms up. Turning her up to full eighteen hundred revs don’t gain while she’s cold, and it throws dust like sin!”

Or, as Larry taxied, learning to manage speed on the ground by use of wider throttle for more speed, cutting down the gas if the craft began going too fast, he would catch an error:

“Did you forget last time to put the stick back and make the blast on the elevators hold the tail down while we taxi? Sure, you did—but you won’t again, because you saw that if you didn’t we might nose over. You ‘over-controlled’, too, and almost nosed over before you caught it—and then, we were going so fast I don’t know what kept this-here crate from starting to hop.
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“That’s right—easy movements always—don’t jerk the controls—take it fairly easy. And you are doing right to move the stick back to neutral this time when the tail came up—kick rudder a bit, isn’t she slanting to the right? That’s it, buddy, left rudder and back, and now the right rudder—there she is, headed right.”

Mostly, Larry caught his own mistakes in time.

Ordinarily cool-headed, he had to be told only once or twice, and reminded almost never that jerky manipulation of the controls was not good practice or helpful to their evolutions. Easy movements, continual alertness and a cool head stood him in good stead.

Seeing those fine qualities, Jeff had Larry thrilling and happy on the fourth day by letting the youthful enthusiast for aviation take over for a simple control job, straight, level flying.

“You’ll want to get the feel of ............