Once more I sought the booking office at Euston.

“The Express has left Prince’s Stage at Liverpool, sir. Will be here in about three hours now, sir,” was the response to my question.

I turned away, dismissed my cab, and started out through the great pillars of the entrance. Three hours more and Dorothy would be here. Tom and I, with the wave-measuring machine, had taken the first boat, which happily left the evening after our interview with Ordway. Dorothy, following a week later, had arrived at Liverpool and was speeding to London. It had been hard to wait the week, filled as it had been with work, but it seemed as if these last hours would never go. Three hours to wait! I had paced the platform of Euston for two already, and I walked out now towards Bloomsbury, passing slowly through its pleasant squares, and watching the foliage behind their guarding railings. Before I knew it, I was in front of the British Museum, and I glanced at my watch. “As good a place to wait as any,” I said to myself, and I crossed the courtyard and started up the steps. Just then a man, hurrying out, slipped at the top of the stone steps and fell heavily, striking his head and lying unconscious where he fell. As it chanced, I was the only spectator, save for a single policeman, and, as I hurried forward, I noticed a Theta Sigma Rho fraternity pin on the waistcoat of the fallen man. I reached him first, the policeman coming up a second later, and together we raised the unconscious form and carried the man to an office, where we placed him on a lounge. I read the name on the reverse of his pin. “E. S. Hamerly.” As he lay there, breathing heavily, I watched him with that interest which a fellow countryman, and far more than that, a member of one’s own fraternity, in distress in a foreign land inspires. He was a clean-cut young fellow, neatly but very simply clad, and I noticed a red acid stain on his sleeve. I had time for no more, for the doctor came hurrying in.

“Only a scalp wound,” he said, as he made his brief examination. “I can bring him round in a minute.”

A vigorous application of cold water, an aromatic to his nose, and the patient sneezed and opened his eyes. As he gazed around I stepped forward.

“Mr. Hamerly,” I said, “I’m Orrington of Columbia. I’m a Theta Sigma Rho man, myself, as I see you are. You’ve had a nasty fall, but you’re coming out all right. I’m going to see you home.”

Hamerly smiled rather wanly. “I don’t feel very energetic,” he said. “I’d be mighty glad to have you. I’m in lodgings up on Half-Moon Street.”

The doctor broke in. “That’s enough talking for the present. Let me fix up your head and you can go all right.”

While the doctor bandaged Hamerly’s head, I signalled a hansom, and in a few minutes we were speeding off to Half-Moon Street.

Too much shaken up by his fall for conversation, Hamerly lay back against the cushions till we reached his lodgings, but he arrived there without seeming any worse for the trip. I saw him safely to bed, promised him an early visit, and left a call for a near-by doctor. Then I looked at my watch. Barely time to reach Dorothy’s train. “To Euston. Rush!” I cried to the cabby, and away we sped. Just as the train came puffing in, I reached the platform, and there was Dorothy’s dear head leaning from the window of her car. The black old station was transformed as she stepped lightly to the platform, followed by her maid. She came towards me with both hands outstretched. “Oh, Jim, it’s good to see you. Where’s Tom?”

“Down at Folkestone,” I answered. “We’ll join him there as soon as you’ve had a night’s sleep.”

“Why wait for that?” asked Dorothy energetically. “It’s only twelve now. We can run down there after lunch. Where are our rooms?”

“At the Savoy,” I said. “Suppose you send your maid up there with the luggage, and we go up in a hansom.”

It took scarcely ten minutes to load the maid and the luggage in a four-wheeler and join Dorothy. As we swung out through the gates, she spoke with a long breath. “It seems good to be back in London again, even with war so near and with so much ahead of us. Now, tell me everything that’s happened since you came over to London from Portsmouth. I got your letter at Queenstown telling about your experiences on the bottom of the sea. How I wish I could have been there. But never mind that now. Tell me all you’ve done in the last four days.”

I settled down to my task. “Tom and I came over safely, as you already know, from our wire at Queenstown. We decided that ‘the man’ would be working in the Channel and, after some discussion, settled on Folkestone as the base from which to work the wave-measuring machine. We took the apparatus down there three days ago, got a big room and set it up. I chartered a yacht.”

“What did you do that for?” interrupted Dorothy.

“So we could run down ‘the man’ if he was on the sea. We decided, coming over, that he was more likely to do his experimenting on water than on land, and Tom thinks he can get him from his experimental waves.”

“I see,” said Dorothy. “Go ahead.”

“After chartering the yacht, I helped Tom all I could till last night, when I came up to London to meet you. Tom expects to get the machine set up to-day. That’s about all.”

“How is the war progressing?” asked Dorothy. “Everybody on board the liner was greatly afraid it would begin before we got across, and that we might be captured, but we reached Liverpool all right.”

“Nothing’s happened yet,” I answered. “But I think it’s coming, may come any minute. They say that the Emperor has refused to see visitors, since the Kaiserin Luisa went down, and I think the government expects war immediately. They’re mobilizing rapidly on both sides.”

“Then there certainly isn’t a minute to lose in reaching Folkestone,” said Dorothy decisively. “We’ll just stop for lunch and go right down.”

It was a day of wonders. Since the night when we had searched for Joslinn, Dorothy and I had never been alone together. The ride from the station to the Savoy was a glorified pilgrimage; the lunch, as we sat looking out on the embankment bathed in sunshine, was a celestial repast, even the time of waiting in the hotel for Dorothy to condense her luggage, and make ready for the coming trip, was a delight. But best of all was the trip down to Folkestone. The guard smiled widely at the golden sovereign which saved the compartment for us, and the porter heaped attentions on us for his tip, but the value which they purchased was priceless. Two hours of speeding through the lovely English country in a tÊte-À-tÊte with my lady.

All too soon came Folkestone, and there beside the train was Tom. “I’ve got him,” he whispered excitedly. “Hurry up, it’s just time to take another reading.”

As we bowled along through the old streets, Tom hurriedly told us of his experience. “He’s experimenting constantly now,” he said. “He sent off some waves yesterday afternoon about four o’clock, just after I got the apparatus going; sent off some more about ten, and some this morning, a little after nine. They’re all from some place out in the Channel, over towards the French coast. They’re from practically the same spot, so I got everything ready for an instant departure on our little boat, and the moment we hear from him again, we’ll start straight for him.”

Dorothy’s eyes sparkled with excitement. “I’m so glad I got here. I wouldn’t miss the end for anything.”

“But you’re not going with us on the yacht?” I said anxiously.

“Of course she’s not,” said Tom gruffly.

“Well, I am,” said Dorothy, “and that’s all there is about it.”

Tom and I broke out in a jumble of incoherent objections, which Dorothy met with smiling assurance.

“You think ‘the man’ may be desperate if we find him,” she said. “Well, I don’t for a minute believe he will be. He’s doing too big a thing to have anything against ordinary people, and if something did happen, you’d need me to protect you.”

Ten minutes more of the drive brought ten minutes more of heated discussion, but it brought us no victory, and the end of the debate came when Tom gave in with the brotherly remark: “Well, go your own confounded, obstinate way then.” To which Dorothy, as calm and smiling as a summer morn, responded simply, “I shall.”

“Here’s our place,” said Tom, as we rattled up to a house which displayed on the stairs to the second story a sign, “Dancing Academy.” “This was the only room we could get that had incandescent wiring, and that was long enough to hold the scale of the Denckel apparatus,” he explained to Dorothy, as we crossed the bare floor to the apparatus, standing in front of the chairs whereon was wont to repose the beauty and chivalry of Folkestone, at the “assemblies” advertised below.

“The machine is working beautifully. Look at this.” He threw the switch, lighted the lamp, and lowered the green shade. The belt of metal had revolved scarcely a minute, and Tom was pulling down the last shade, as the beam fluttered and the machine stopped. “Just in time,” said Dorothy delighted. “Hurry up, Tom.” The old inherent passion of the chase was on us all, and in less than twenty minutes, the last figures made, Tom and Dorothy compared their work.

“Just there,” said Tom, making a cross with his pencil on a point on the French coast some ten miles up from Boulogne. “Come on, don’t waste a minute. It’s practically a straight run across the channel.”

Ten minutes brought us aboard the little yacht and ten minutes more saw us steaming out of the harbor. Dorothy was with us. Further discussion had been useless.

“Not much like the Black Arrow,” I said, as we came out rather slowly into the Channel.

“You wait till she gets speeded up,” said Tom. “She can go. I proved that yesterday.”

He was right. Once out into the Channel, our speed gradually increased, till we were making good progress. In an hour we sighted the French coast from the little bridge, and Tom, beside the skipper, was making for the cross on the chart.

“We’ll sight her, if she hasn’t gone directly away from us, inside of fifteen minutes,” Tom said. Dorothy stood beside the wheel, ranging the whole horizon with her binoculars. She had thrown aside her hat, and a loosened tress of her hair flew lightly across my face as I stood beside her.

“Two sails off that point,” she announced, in a few moments. “They look more like those tubs of French fishing-boats than a yacht,” she said shortly. “Look at them, Jim.”

She handed her glasses to me. The horizon, for five miles in any direction from the point where we were heading, showed but the two sails she had mentioned, and we headed directly for them. As we neared them, we saw that Dorothy’s eyes had proved true. They were wide, clumsy, fishing craft, such as sail from the harbor of Boulogne, or hang in miniature as votive offerings before the altars of the cathedral. Undecked and open, they could hold no complicated apparatus. Their crews were sturdy, jerseyed fishermen, who stared in open-mouthed wonder, as our yacht came up alongside the first, and a volley of questions came in rapid French from the beautiful girl on the bridge.

With instinctive courtesy, every sailor on either boat removed his cap as she spoke, and the skipper gave answer in slow, deeply considered words. “No, we have seen no yacht except your own. Hein! is it not so?” he turned to the sailors.

A chorus of affirmatives came back. There had been no other vessel off this point save the Virginie of their own town, (an expressive thumb pointed to the other boat,) for four, five hours. They would surely have seen it if there had been. Tom consulted his chart and consulted our own skipper. It was the very spot. With knitted brow, he ordered the boat headed for the other fishermen. I pulled a half sovereign from my pocket.

“Buvez avec moi, mes garÇons,” I cried, and flung the coin into the fishing boat. A chorus of “Merci’s” followed our path.

The other boat gave no better results. Its sailors had seen nothing, and we ran back to the point whence the waves had come, for a brief consultation. As we gazed on the quiet water just tinged with the last of the sunset, I spoke.

“There’s only one explanation, if the wave-measuring machine is correct. He’s down on the bottom in a submarine, or he was there when he sent off those waves.”

“I’m afraid that’s right, Jim,” said Tom. “If I could only see down there. I wonder how deep it is.” He called to the captain. “Take a sounding here, will you please?”

We hurried forward and watched the line overboard. Fathom after fathom disappeared up to the very end. “It’s more than a hundred twenty fathom, sir,” reported the captain.

“No use, then,” said Tom. “Go right back to Folkestone. We’ll have a couple more tries to-morrow,” he went on. “But, frankly, I’m afraid it won’t do any good. To find a submarine in these waters would be worse than finding a needle in a haystack.”

It was a rather gloomy little party that landed at Folkestone that night. We had seemed so near success. Yet there was one alleviation. I had dreaded bringing Dorothy into danger, and I had had a most uneasy feeling as to the possible result of the meeting with a man inspired with so fixed and fearful a purpose as he whom we sought. Much as I desired the completion of my search, I could not therefore feel too complete a sense of regret at the two failures which we encountered on the Channel the next day. The man was in the Channel sea. He was experimenting with his apparatus daily under its waves. We could be sure of that, but he could not be reached, so we finally gave in and returned to London.

All the way up in the train, Dorothy sat in deep thought, but no result came from her meditations, and we returned to the Savoy without a ray of light as to our next move.

The next morning I woke with fresh courage. We had gained so much and so unexpectedly, that I felt convinced we must gain more. I found a table in the dining-room, and waited there for Tom and Dorothy, who shortly appeared. We breakfasted gaily. The morning sun shone brightly on the little park below the window and on the Thames, flowing slowly beyond. The peaceful scene looked little like war, but the papers before us were full of dire forebodings. The German Emperor still sulked. Movements of army corps and of battleships were the main part of their story. Despite the columns filled with martial things, every newspaper had at least one reference to the man who was trying to stop all war, and in more than one of them was a word as to the double danger of the fleets, who faced not only a foreign foe, but annihilation at the hands of this unseen destroyer. As we finished breakfast, Dorothy asked, “What are you boys going to do this morning?”

“I must go down to the city to get some money,” I replied.

“I think I’ll do the same,” remarked Tom.

“We’ll all go together, then,” said Dorothy.

As we passed out into the courtyard, I raised my stick for a cab, but Dorothy stopped me. “Let’s go down on top of a bus. I haven’t been on one since I landed, and we’re in no hurry.”

Up the winding stair we climbed, and Tom and Dorothy found a seat beside the driver, while I was just behind. Down the Strand into Fleet Street we passed, through the crowds before the bulletins, watching anxiously for the message which should spell “War.” At the top of Ludgate Hill, just by St. Paul’s, came a block, one of those hopeless tangles which so completely ties up London traffic. Another bus stood just ahead, and I read off the big advertisements which lined its top. “Alhambra Radium Ballet,” I read. “There’s a scientific scheme for you people. What is a radium ballet, anyway?”

“Oh, they cover the girls’ dresses with phosphorescent paint, and turn out the lights,” said Tom. “It’s an old idea. They had them ten years ago.”

Dorothy turned suddenly. “That’s what we want. It’s the very thing we’ve been hunting for, the new clue. We’ve never run that down, at all.”

Tom and I followed slowly her quick intuition. “What new clue?” I asked.

“The phosphorescent paint clue,” answered Dorothy energetically. “‘The man’ wrote his first message with a peculiar type of phosphorescent ink. He must have been working with it for some time. If we can only find anybody that knows about that kind of paint, we might find out something more definite about him. It’s the best clue we have, anyway.”

“But how will you get hold of the people who know about phosphorescent paint?” said Tom. “I think you’re in the blindest alley yet.”