by Van Powell
CHAPTER XXI
A QUESTION OF ANGLES
Without wasting an instant, when he saw the silhouette of the spectrein the cloud, Don fired the Verey pistol set at the side of hisairplane.
Arranged for the discharge of the Verey lights, the implement, fixed atone side of the fuselage, sent out into the air a bright, white flash.
The smoke bomb that Don used was such as pilots employ to show themwind direction. The light was almost instantly gone, being succeeded bythe liberation of a dense volume of smoke that drifted in the lightSummer breeze. But Don was not concerned with the smoke: he knew thatwatchful eyes had been ready to catch the flash, through the dark.
"They know, in the control room, that I got what I came for," he toldhimself. "Now they'll shut off the light and get everything put awaybefore the control man returns from his late supper."
With quick hands he set the controls to swing back, and made the returntrip in as brief a space of time as the Dart's power permitted.
At the runway, as he came to rest, Chick ran up.
"We got your flash!" he said, keeping his voice low. "Garry's puttingback the things. Let's get the Dart back. You'll have to explain theflight to the control man. He must have heard the take-off and landing."
"Right. Well, Chick, one thing is settled, anyhow."
"One thing? You mean----"
Don, unsnapping his helmet chin strap, put his lips close to Chick'sear and spoke very earnestly.
"The spectre appeared. But!--it wasn't from your projector!"
If he expected a cry of surprise, as his grip on Chick's arm for awarning seemed to indicate, he was, himself, surprised.
"We know it," Chick, to Don's amazement remarked.
"You do? Then you saw it?"
"No, Don. Come on. Let's not talk till we get back to Garry."
He led the way to the stairs, and instead of going on to the controltower, turned aside at the door to the lower corridor.
"Let's go into the designing department," he suggested. "As soon as thecontrol man returns, Garry will meet us there."
"Just where I meant to go."
Together they entered the room, lighting its dome bulbs.
"As soon as I saw the picture on the cloud," Don stated, "I knew itdidn't come from the control room."
"How did you find that out!"
Don, at the table, took pencil and paper.
While he sketched rapidly Garry entered. Chick put him in possession ofDon's news.
Watching, Garry nodded.
"Don knew, from the light angle, I guess," he whispered.
The sketch Don made was proof of his accuracy of judgment.
It showed a small airplane, as though viewed from above. Its nose wasdirected toward a sketchy line that indicated the shore of the bay.
A little in front of its nose Don had made a small indication of acloud. On that he put a straight line, that the others saw was meant torepresent the "screen," or place where the picture had been seen.
And the airport control room when he sketched it in, lay at exact rightangles to that screen line!
"As the nose pointed West," Don said, excitedly, "the light from yourprojector, coming from the South, would have been on the South part ofthe cloud. But the picture was on the East side, the one I faced.That's how I knew you didn't throw the picture. Besides, as I sawearlier, the diffused light from your beam, as it touched a cloudbefore the picture appeared, was very faint!"
"Q. E. D." Chick quoted his school algebraic phrase.
"But if I saw the picture facing toward the West, how could you see itfrom the South!" asked Don.
"We didn't!"
"Then how did you know, Garry? What proved you didn't project it?"
Garry answered slowly.
"The film we had," he explained, "started off with a couple of 'shots'of airplanes--flying over our swamp. But then it became a series ofmoving pictures, taken from the air, of water and marsh."
"And that was all," Chick added.
"The more things I see," Don said after a long moment of thought, "themore I begin to think that Indian, John, had the right idea."
"About Smith--the mail flyer?" Garry asked.
"Yes."
"We will see a little later," Chick stated. "His 'plane comes in afterawhile."
"Don't forget," Don argued, "that a man clever enough to do all thethings we have seen done is bright enough to have somebody else fly hismail close to this airport, set down, and let Smith take it over andbring it in. For money, and with a man far enough away, it would bepossible--and we could never check it up."
"He's still in that swamp, close by," Don argued. "He is as brazen asthey come, too!" Chick wondered audibly why Don had not flown straightup "to catch the man."
"Alone?" Garry defended Don from a hint of caution. "Don did the rightthing, coming back here. The stores haven't reported a call for sparecarburetor parts. The man is clever."
"Maybe he got spare parts at Bennett Field, or Roosevelt Field," Chicksuggested.
Don held up a hand and shook his head.
"It isn't important, just now," Don declared. "Let's make sure how thepicture was thrown, tonight, while I flew around. Then we can work outwhy there is this extra projector head and a misfit airplane crashpicture afterward, and about the carburetor."
"Well, if you looked around, you must have seen the crate that the'ghost' used," Chick inferred.
"But I didn't."
They knew that he had not been careless: had a ship been in sight hissharp eyes, looking for just that, would have noted it.
"Listen," Garry drew up a chair by the table, "Don, your knowledge ofangles, and the things you had to study about angle of attack of awing, and angles of incidence of air and wing, and all that, ought tohelp out here. This seems to be a question of angles."
"It does," Chick agreed. "What's more, Garry, you've studied aboutlight, because I know the control chief gave you some books when he sawthat you took an interest in his work."
"Maybe we can both get something out of what we've learned," Donadmitted. "Now--how?"
"Well," Chick offered an opinion, "the old Indian gave us passes thatshowed us 'how' the ghost could be worked. Maybe there is a clue to'where from.'"
"Yes--I think there is!" Don caught a fresh sheet of paper, and beganto draw a rough diagram of the theatre stage, sketching in the positionof the pillar of smoke broadly.
"From what we've proved, about tonight, the stage picture couldn't havecome from the wings," he stated. "It would have to fall on the smokefrom the front, almost, or else the people in side seats might see itand not those in direct line, from in front of it."
Garry drew the sheet to him, made an addition, showing the projectionroom of the Palace, up on its balcony.
"The theatre was made very dark," he said, "and all the light on thestage was adjusted so that the sunset died out when the pillar of smokewent upward. Then the man at the film projectors in the balcony 'fadedin' the picture--from in front, and at an angle 'above' the audience."
Don jumped up, upsetting his chair in his excitement.
"Knowledge is Power!" he cried, excitedly. "Study of angles has givenus the answer to Chick's 'where from!' That shows why there is ahelicopter hidden in the marsh!"
"I see it!" Chick was equally animated. "With the helicopter, the'ghost' projector could hover above the clouds, well hidden."
"Yes, and 'throw down' from that makeshift 'projection room' onto acloud," exclaimed Garry.
"He could hover very high," Don contributed. "There he could see anairplane, coming, at a distance, gauge its direction, swing his ownship and descend to a point over a cloud. Hidden there, with his lighton, and his film going through, the spectre would appear on smoke orclouds right in front of the coming airplane."
"That's exactly how, and from where, the ghost comes!" Garry agreed."Now, here's a suggestion, Don! Let's 'show' everybody!"
"
I don't quite see--" began the young pilot.
"It's almost midnight." Garry consulted his wrist watch. "The Palacehas finished the second show. The control chief and the others will allcome here to see that everything is right, and for the arrival of themidnight passenger 'plane from the Maine Summer resorts. I'll stay hereand you, Don, and Chick, take the Dart, fly to where the helicopter is,with the projector and film, and when I give a beam signal that theyare here, you two, in the helicopter, pick a cloud they can all see,and 'put on your show.' The minute that everybody sees how simply it isdone, the ghost's claws will be pulled--no pilot will be afraid andmaybe--maybe your uncle will get a whale of a lot of business."
"Yes!" Chick was enthused. "And Garry can see whose face betrays guiltyknowledge, when the actual 'spook' is projected."
"But--" Don saw the difficulties, "this isn't the same film, hidden inthe locker. Besides--where will we get the light?"
"The 'ghost' must get light from somewhere--" Chick began.
A flash of inspiration made him bang his palm on the table.
"The boathouse!" he exclaimed. "Don--Garry! I saw the Man who NeverLived come up from under that boathouse. That's where he stores all hisreal stuff--light, and film, and maybe another projector, complete!This one is just in case he is suspected--to mix up the trails!"
"I believe Chick has the right idea!" Garry conceded.
"So do I! Come on, Chick! We'll 'put on a show' and clear up theairport mystery of the spectre in the clouds for once and all!"
Again the faithful Dart, with two youthful occupants, took to the air.
And someone, behind the screen at the wash basin in the designing room,smiled, waited until Garry left for the control room, and then strollednonchalantly back to the cottage where he roomed, and went peacefullyto his quarters.
"There won't be any more need for the ghost," remarked the quietlysmiling person to his shaving mirror. "Tomorrow the boys will be busygetting out of this little experiment--the engineers won't be working,and it ought to be easy to find the chest that must have been buriedwhen the mud in Crab Channel sucked down the brigantine, _Lady O'Fortune_."
Don and Chick, in the Dart, drove on, full-gun, to help his prophecycome true.
