CHAPTER IX-THE CIPHER
"What happened to you?" asked Jack and Dick in chorus.
Swiftly Harry explained. He told of his arrest as a spy and of hisescape. And when he mentioned the part that Ernest Graves had played inthe affair, Jack and Dick looked at one another.
"We were afraid of something like that," said Jack. "Harry, we've foundout a lot of things, and we don't know what they mean! We're suresomething dreadful is going to happen to-night. And we're sure, too,that Bray Park is going to be the centre of the trouble."
"Tell me what you know," said Harry, crisply. "Then we'll put two andtwo together. I say, Jack, we don't want to be seen, you know. Isn'tthere some side road that doesn't lead anywhere, where I can run in withthe car while we talk?"
"Yes. There's a place about a quarter of a mile further on that will dosplendidly," he replied.
"All right. Lead the way! Tell me when we come to it. I've justthought of something else I ought never to have forgotten. At least, Ithought of it when I took the things out of my pockets while I waschanging my clothes."
They soon came to the turning Jack had thought of, and a run of a fewhundred yards took them entirely out of sight of the main road, and to aplace where they were able to feel fairly sure of not being molested.
Then they exchanged stories. Harry told his first. Then he heard ofDick's escape, and of his meeting with Jack. He nodded at the storythey had heard from Gaffer Hodge.
"That accounts for how Graves knew," he said, with much satisfaction."What happened then?"
When he heard of how they had thought too late of calling ColonelThrockmorton by telephone he sighed.
"If you'd only got that message through before Graves got in his work!"he said. "He'd have had to believe you then, of course. How unlucky!"
"I know," said Jack. "We were frightfully sorry. And then we went outto find where the wire was cut, and they got Dick. But I got away, andI managed to stay fairly close to them. I followed them when they leftDick in a little stone house, as a prisoner, and I heard this-I heardthem talking about getting a big supply of petrol. Now what on earth dothey want petrol for? They said there would still be plenty left forthe automobiles-and then that they wouldn't need the cars any more,anyhow! What on earth do you make of that, Harry?"
"Tell me the rest, then I'll tell you what I think," said Harry. "Howdid you get Dick out? And did you hear them saying anything thatsounded as if it might be useful, Dick?"
"That was fine work!" he said, when he had heard a description of Dick'srescue. "Jack, you seem to be around every time one of us gets intotrouble and needs help!"
Then Dick told of the things he had overheard-the mysterious referencesto Von Wedel and to things that were to be done to the barracks atEaling and Houndsditch. Harry got out a pencil and paper then, and madea careful note of every name that Dick mentioned. Then he took a paperfrom his pocket.
"Remember this, Dick?" he asked. "It's the thing I spoke of that Iforgot until I came across it in my pocket this morning."
"What is it, Harry?"
"Don't you remember that we watched them heliographing some messages,and put down the Morse signs? Here they are. Now the thing to do is tosee if we can't work out the meaning of the code. If it's a code thatuses words for phrases we're probably stuck, but I think it's morelikely to depend on inversions."
"What do you mean, Harry?" asked Jack. "I'm sorry I don't know anythingabout codes and ciphers."
"Why, there are two main sorts of codes, Jack, and, of course, thousandsof variations of each of those principal kinds. In one kind the idea isto save words-in telegraphing or cabling. So the things that are likelyto be said are represented by one word. For instance _Coal_, in amining code, might mean 'Struck vein at two hundred feet level.' In theother sort of code, the letters are changed. That is done in all sortsof ways, and there are various tricks. The way to get at nearly all ofthem is to find out which letter or number or symbol is used most often,and to remember that in an ordinary letter E will appear almost twice asoften as any other letter-in English, that is."
"But won't this be in German?"
"Yes. That's just why I wanted those names Dick heard. They are likelyto appear in any message that was sent. So, if we can find words thatcorrespond in length to those, we may be able to work it out. Heregoes, anyhow!"
For a long time Harry puzzled over the message. He transcribed the Morsesymbols first into English letters and found they made a hopeless andconfused jumble, as he had expected. The key of the letter E wasuseless, as he had also expected. But finally, by making himself thinkin German, he began to see a light ahead. And after an hour's hard workhe gave a cry of exultation.
"I believe I've got it!" he cried. "Listen and see if this doesn'tsound reasonable!"
"Go ahead!" said Jack and Dick, eagerly.
"Here it is," said Harry. "'Petrol just arranged. Supply on way. ReachBray Friday. Von Wedel may come. Red light markers arranged. EalingHoundsditch Buckingham Admiralty War Office. Closing.'"
They stared at him, mystified.
"I suppose it does make sense," said Dick. "But what on earth does itmean, Harry?"
"Oh, can't you see?" cried Harry. "Von Wedel is a commander of somesort-that's plain, isn't it? And he's to carry out a raid, destroying orattacking the places that are mentioned! How can he do that? He can'tbe a naval commander. He can't be going to lead troops, because we knowthey can't land. Then how can he get here? And why should he needpetrol?"
They stared at him blankly. Then, suddenly, Dick understood.
"He'll come through the air!" he cried.
"Yes, in one of their big Zeppelins!" said Harry. "I suppose she hasbeen cruising off the coast. She's served as a wireless relay station,too. The plant here at Bray Park could reach her, and she could relaythe messages on across the North Sea, to Heligoland or Wilhelmshaven.She's waited until everything was ready."
"That's what they mean by the red light markers, then?"
"Yes. They could be on the roofs of houses, and masked, so that theywouldn't be seen except from overhead. They'd be in certain fixedpositions, and the men on the Zeppelins would be able to calculate theiraim, and drop their bombs so many degrees to the left or the right ofthe red marking lights."
"But we've got aeroplanes flying about, haven't we?" said Jack."Wouldn't they see those lights and wonder about them?"
"Yes, if they were showing all the time. But you can depend on it thatthese Germans have provided for all that. They will have arranged forthe Zeppelin to be above the positions, as near as they can guess them,at certain times-and the lights will only be shown at those times, andthen only for a few seconds. Even if someone else sees them, you see,there won't be time to do anything."
"You must be right, Harry!" said Jack, nervously. "There's no other wayto explain that message. How are we going to stop them?"
"I don't know yet, but we'll have to work out some way of doing it. Itwould be terrible for us to know what had been planned and still not beable to stop them! I wish I knew where Graves was. I'd like-"
He stopped, thinking hard.
"What good would that do?"
"Oh, I don't want him-not just now. But I don't want him to see me justat present. I want to know where he is so that I can avoid him."
"Suppose I scout into Bray?" suggested Jack. "I can find out somethingthat might be useful, perhaps. If any of them from Bray Park have comeinto the village to-day I'll hear about it."
"That's a good idea. Suppose you do that, Jack. I don't know just whatI'll do yet. But if I go away from here before you come back, Dick willstay. I've got to think-there must be some way to beat them!"