Chapter IV. A Wolf on the Trail
 

"That isn't Ned!" cried Jack's voice, in a moment.

"Don't let him get away! He's been up to some mischief!"

That was Frank Shaw's voice.

"Soak him!"

That could be no one but Jimmie!

Ned, groping about in the darkness, heard the voices faintly. He seemed to be submerged in a sweep of pounding waves, the steady beating of which shut out all individual sounds.

He knew that he staggered and stumbled as he walked. Moving across the floor his feet came in contact with some soft obstruction lying on the rug and he fell down.

There was a strange, choking odor in the place, and he groped on his hands and knees in the direction of the shelf where his searchlight had been left. His senses reeled, and for an instant he lay flat on the floor.

Then he heard the boys clambering down the stairs from the conning tower and called out, feebly, yet with sufficient strength to make himself heard above the sound of shuffling feet.

"Go back!" he cried. "Don't come in here! Leave the hatch open, and let in air. Go back!"

Jimmie recognized a note of alarm, of suffering, in the voice of his chum and dropped headlong into the black pit of the submarine. Ned heard him snap the catch of a searchlight, and then, dimly, heard his voice:

"Gee!" the voice said. "What's comin' off here?"

The round face of the electric searchlight showed at the end of a cylindrical shaft of light which rested on Ned's face, but the boy did not realize what was going on until he felt a gust of wind and a drizzle of rain on his forehead.

Then he opened his eyes to find himself on the conning tower of the submarine, with the boys gathered about him, anxiety showing in their speech and manner. It was too dark for him to see their faces.

"You're all right now," Jimmie said. "What got you down there?"

Then Ned remembered the sudden extinction of the lights as he moved down the stairs, the stifling, choking odor below, and the deadly grip of suffocation which had brought him to the floor.

"Go back into the boat," he said, gaining strength every moment. "I am anxious about Lieutenant Scott."

"We've just come from there," Frank said. "We've done all that can be done for him."

"What do you mean by that?" demanded Ned, moving toward the hatch which sealed the submarine.

"The poison which keeled you over got him!" Jack said.

"Do you mean that he's dead?" asked Ned, a shiver running through his body as he spoke.

"I'm afraid so," was the reply. "We got you out just in time. You would have perished in a moment more."

"Dead!" said Ned. "Lieutenant Scott dead! And he was so gay and so full of life a few moments ago!"

Jack, who had left the little group a moment before, now returned.

"The poison seems to have evaporated from the interior," he said, "so we may as well go below. I'll go ahead and turn on the lights." The body of the naval officer lay in a huddle at the foot of the stairs leading to the conning tower, just far enough to the rear so that the free passage was not obstructed. With all the lights turned on and every aperture which might transmit a ray to the world outside closed, the boys, after placing the body on a couch, began a close examination of the boat.

There were no wounds on the body, so it seemed that he had died from suffocation. There was still a sickening odor in the boat, but the constant manufacture of fresh air was gradually doing away with this.

The door to the room where the dynamos and the gasoline engine were situated was found wide open, and Ned instructed the boys to leave it so and leave everything untouched.

"The first thing to do," he said, "is to discover any clues the assassin may have left here. It is an old theory that no person, however careful he or she may be, can enter and leave a room without leaving behind some evidence of his or her presence there. We'll soon know if this is true in this case."

"There was some one in here, all right," Jimmie said. "He passed us on the conning tower, skipping like to break the speed limit for the city. I tried to trip him as he passed me, an' got this."

The lad turned a bruised face toward his companions. In the confusion no one had observed the cut on his cheek.

"You did get something!" Jack exclaimed. "Why didn't you say something about it?"

"Nothin' doin'!" answered the boy. "Only a scratch!"

Notwithstanding the boy's claim that the wound was of small importance, Ned insisted on its being dressed at once.

"Now," Ned said, after the cut had been properly cared for, "what sort of a man was it that passed you boys on the conning tower? The circular platform is so small that he must have crowded you pretty closely when he stepped out."

"He did," Jimmie answered. "I thought it was you, and stepped aside to make room for him."

"And then?"

"I had a feeling that it wasn't you. Then, he was makin' for the wharf so fast that I thought it would do no harm to have a look at him, and so called out."

"Then's when you got the slash across the cheek?"

"Yes; he cut me then."

"What about the size of the fellow?" asked Ned.

"Oh, I should think he was slender and light, the way he bounded off the platform and made for the wharf."

"Do you think he went there to kill Lieutenant Scott?" asked Jack, a moment later.

"It is more probable that he came here to put the Sea Lion out of commission," Frank replied.

"I'll bet well find somethin' all busted up!" Jimmie predicted.

"Ned can soon determine that," Jack remarked.

"Yes," Ned went on, "but the first thing to do is to see if this murderer left any visiting cards here. After that, we must notify the Coroner and have the body removed."

Ned went into the dynamo room and looked about.

"Here is where any enemy would have to do his work," he said, "so we must look for clues here. Keep your hands off the machinery, for he may have left finger marks somewhere."

Ned searched long and carefully without reward. Finally he turned to the waiting boys.

"There's quite a lot of waste lying around," he said. "Secure every fiber of it and examine it under the microscope. You would better attend to that, Frank, as you are familiar with the instrument. If you discover anything foreign to a place like this, let me know."

While Ned continued his search about the interior of the submarine, Frank busied himself inspecting the bits of waste the other boys brought to him. At last an exclamation of astonishment brought Ned to his side.

"There's something funny about this," Frank said, as Ned bent over his shoulder. "That stuff is not oil, and I'd like to know how it got in here."

"What does it look like?" asked Ned.

"I can't say," was the hesitating reply.

Ned took the microscope and looked at the object to which his attention had been called.

"Rubber!" he said, in a moment.

"Rubber!" repeated Frank. "How could rubber be in the waste in that shape?"

"All the same," Ned replied, "this is some rubber composition, and it has been wiped into the waste. Now, what could any person want with rubber here?"

"It is used quite a lot around electric apparatus," suggested Frank Shaw.

"But not in this form," Ned replied.

Then, remembering certain smooth blurs on the polished machinery he had recently examined, he took the microscope and made another examination of the spots. Presently he called Frank to his side.

"Look through the glass," he said, handing the instrument to Frank, "and tell me what you see."

"Rubber!" cried the boy, after a short examination. "There are a few traces here of the same rubber composition I found on the waste. Can you tell me what it means?"

"Quite simple," Ned replied, as the boys gathered about him. "The use of rubber composition by men engaged in nefarious undertakings dates back to the time of the utilization of the whorls and lines of the human fingers as aids in the detection of crime."

"I guess I know what you are going to say," cried Frank.

"When the thumb- and finger-print experts got busy with their photographs and their enlarged reproductions, the criminals began studying on methods to offset this dangerous aid to detective work."

"I knew it," cried Frank.

"And so," Ned went on, "they conceived the idea of filling the lines on the fingers and hands and making them perfectly smooth. This is rubber paint," he went on. "The man who was hidden in here when we came in did not care to leave any finger marks behind him."

"But he did leave smooth blurs on the machines where his fingers touched them!" said Jack.

"Certainly, and so pointed out the location of his efforts. Still, I do not think he meditated disabling the Sea Lion. It is more probable that he believed Lieutenant Scott to be the expert in charge of the boat and sought to kill or disable him."

"See where the chump wiped his hands on waste," Jimmie cried.

Ned now made a still closer inspection of the room and was rewarded for his thoroughness by discovering a tiny pool of the rubber composition on the floor, close to the giant iron frame of the big dynamo. Looking at the pool through his glass he discovered bits of wool mixed with it. He put up his glass with a smile.

"We ought to be able to find this fellow now," he said, "if we get busy before he has time to change his clothes."

"Got him, have you?" asked Jack.

"I think I could pick him out of a thousand provided he is captured in the clothes he wore while here. His hand trembled while he was putting the rubber composition on his fingers and some of it dropped on his clothing and dripped off to the floor.

"There are shreds of blue wool in this composition on the floor--so you see he wore a blue woolen garment--probably a coat or pair of trousers. And, see here, the fellow lost all caution when he bounded out of the submarine, after extinguishing the lights, on my entrance.

"He had already wiped the rubber off his hands on the waste, and so his finger marks showed on the steel railing of the staircase. I'll just take a photo of them."

When this was accomplished, Ned and Jimmie drew the Sea Lion's boat to the edge of the float and launched it. Then, leaving Frank and Jack in charge of the submarine, with instructions to keep a close watch for suspicious characters, they turned the prow of the rowboat toward South Vallejo. The distance to the wharf was not great. In fact, the intruder seemed to have cleared it in a minute, either in a boat, which was improbable, or by swimming.

The Sea Lion lay off the United States Navy Yard, on the west of Mare Island, in the straits of the same name. The nearest landing place on the mainland, therefore, was South Vallejo.

It was after 8 o'clock when the boys reached the main street of the town and encountered a policeman in uniform. Ned at once asked for the office of the Coroner of Salano County.

"What's doing?" asked the policeman.

"I have business with him," Ned replied, not caring to create a sensation by reciting there in the street the details of what had taken place.

"Well," replied the policeman, "if you're so mighty close-mouthed regarding your business with the Coroner, you may find him yourself."

"All right," Ned replied. "I'll go to police headquarters. Perhaps the night desk man won't be so fresh."

"Say," growled the policeman, "you needn't get gay. I know my duty. So, if you don't mind, I'll take you to headquarters, saving you the trouble of asking for the place."

"I refuse to go with you," Ned replied.

"Oh, well," announced the other, "I'll take you along, just the same. I'm used to kids of your stamp. You're both under arrest, so you'd better come along without making any trouble."

As he spoke the policeman seized both boys roughly.