The letter was most interesting:

PROFESSOR CRAIG KENNEDY, The University, New York City.

DEAR SIR,

Your telautomatic torpedo model was tested yesterday and I take great pleasure in stating that it was entirely successful. There is no doubt that the United States is safe from attack as long as we retain its secret.

Very sincerely yours,

DANIEL WATERS, a.s.s't Sec'y.

"Oh, Craig," congratulated Elaine, as she handed back the note. "I'm so glad for your sake. How famous you will be!"

"When are we going to see the wonderful invention, Craig?" I added as I grasped his hand and, in return, he almost broke the bones in mine wringing it.

"As soon as you wish," he replied, moving over to the safe near-by and opening it. "Here's the only other model in existence besides the model I sent to Washington."

He held up before us a cigar-shaped affair of steel, about eight inches long, with a tiny propeller and rudder of a size to correspond. Above was a series of wires, four or five inches in length, which, he explained, were the aerials by which the torpedo was controlled.

"The principle of the thing," he went on proudly, "is that I use wireless waves to actuate relays on the torpedo. The power is in the torpedo; the relay releases it. That is, I send a child with a message; the grown man, through the relay, does the work. So, you see, I can sit miles away in safety and send my little David out anywhere to strike down a huge Goliath."

It was not difficult to catch his enthusiasm over the marvellous invention, though we could not follow him through the mazes of explanation about radio-combinators, telecommutators and the rest of the technicalities. I may say, however, that on his radio-combinator he had a series of keys marked "Forward," "Back," "Start," "Stop," "Rudder Right," "Rudder Left," and so on.

He had scarcely finished his brief description when there came a knock at the door. I answered it. It was Chase and his a.s.sistant, whom Kennedy had employed in the affair.

"We've found the place on Pell Street that we think is Wu Fang's," they reported excitedly. "It's in number fourteen, as you thought. We've left an operative disguised as a blind beggar to watch the place."

"Oh, good!" exclaimed Elaine, as Craig and I hurried out after Chase and his man with her. "May I go with you?"

"Really, Elaine," objected Craig, "I don't think it's safe. There's no telling what may happen. In fact, I think Walter and I had better not be seen there even with Chase."

She pouted and pleaded, but Craig was obdurate. Finally she consented to wait for us at home provided we brought her the news at the earliest moment and demonstrated the wonderful torpedo as well. Craig was only too glad to promise and we waved good-bye as her car whisked her off.

Half an hour later we turned into Chinatown from the shadow of the elevated railroad on Chatham Square, doing our best to affect a Bowery slouch.

We had not gone far before we came to the blind beggar. He was sitting by number fourteen with a sign on his breast, grinding industriously at a small barrel organ before him on which rested a tin cup.

We pa.s.sed him and Kennedy took out a coin from his pocket and dropped it into the cup. As he did so, he thrust his hand into the cup and quickly took out a piece of paper which he palmed.

The blind beggar thanked and blessed us, and we dodged into a doorway where Kennedy opened the paper: "Wu Fang gone out."

"What shall we do?" I asked.

"Go in anyhow," decided Kennedy quickly.

We left the shelter of the doorway and walked boldly up to the door.

Deftly Kennedy forced it and we entered.

We had scarcely mounted the stairs to the den of the Serpent, when a servant in a back room, hearing a noise, stuck his head in the door.

Kennedy and I made a dash at him and quickly overpowered him, snapping the bracelets on his wrists.

"Watch him, Walter," directed Craig as he made his way into the back room.

In the devious plots and schemes of Wu Fang, his nefarious work had brought him into contact not only with criminals of the lowest order but with those high up in financial and diplomatic circles.

Thus it happened that at such a crisis as Kennedy had brought about for him Wu had suddenly been called out of the city and had received an order from a group of powerful foreign agents known secretly as the Intelligence Office to meet an emissary at a certain rocky promontory on the Connecticut sh.o.r.e of Long Island Sound the very day after Kennedy's little affair with him in the laboratory and the day before the letter from Washington arrived.

Though he was mortally afraid of Kennedy's pursuit, there was nothing to do but obey this imperative summons. Quietly he slipped out of town, the more readily when he realized that the summons would take him not far from the millionaire cottage colony where Elaine had her summer home, which, however, she had not yet opened.

There, on the rocky sh.o.r.e, he sat gazing out at the waves, waiting, when suddenly, from around the promontory, came a boat rowed by two stalwart sailors. It carried as pa.s.sengers two dark-complexioned, dark-haired men, foreigners evidently, though carefully dressed so as to conceal both their ident.i.ty and nationality.

As the boat came up to a strip of sandy beach among the rocks, the sailors held it while their two pa.s.sengers jumped out. Then they rowed away as quickly as they had come.

The two mysterious strangers saluted Wu.

"We are under orders from the Intelligence Office," introduced one who seemed to be the leader, "to get this American, Kennedy."

A subtle smile overspread Wu's face. He said nothing but this adventure promised to serve more than one end. "Information has just come to us,"

the stranger went on, "that Kennedy has invented a new wireless automatic torpedo. Already a letter is on its way informing him that it has been accepted by the Navy."

The other man who had been drawing a cigar-shaped outline on the wet sand looked up. "We must get those models," he put in, adding, "both of them--the one he has and that the government has. Can it be done?"

"I can get them," answered Wu sinisterly.

And so, while Kennedy was drawing together the net about Wu, that wily criminal had already planned an attack on him in an unexpected quarter.

Down in Washington the very morning that our pursuit of Wu came to a head, the officials of the navy department, both naval and civil, were having the final conference at which they were to accept officially Kennedy's marvellous invention which, it was confidently believed, would ultimately make war impossible.

Seated about a long table in one of the board rooms were not only the officers but the officials of the department whose sanction was necessary for the final step. By a window sat a stenographer who was transcribing, as they were taken, the notes of the momentous meeting.

They had just completed the examination of the torpedo and laid it on the end of the table scarcely an arm's length from the stenographer. As he finished a page of notes he glanced quickly at his watch. It was exactly three o'clock.

Hastily he reached over for the torpedo and with one swift, silent movement tossed it out of the window.

Down below, in a clump of rhododendrons, for several moments had been crouching one of the men who had borne the orders to Wu Fang at the strange meeting on the promontory.

His eyes seemed riveted at the window above him. Suddenly the supreme moment for which this dastardly plot had been timed came. As the torpedo model dropped from the window, he darted forward, caught it, turned, and in an instant he was gone.

Wu Fang himself had returned after setting in motion the forces which he found necessary to call to aid the foreign agents in their plots against Kennedy's torpedo.

As Wu approached the door of his den and was about to enter, his eye fell on our outpost, the blind beggar. Instantly his suspicions were aroused. He looked the beggar over with a frown, thought a moment, then turned and instead of entering went up the street.

He made the circuit of the block and now came to an alley on the next street that led back of the building in which he had his den. Still frowning, he gazed about, saw that he was not followed, and entered a doorway.